Chem Soc Rev CRITICAL REVIEW

Chem Soc Rev

Dynamic Article Links

Cite this: Chem. Soc. Rev., 2012, 41, 7590–7604 www.rsc.org/csr

CRITICAL REVIEW

Diphosphates and diphosphonates in polyoxometalate chemistryw Abhishek Banerjee, Bassem S. Bassil, Gerd-Volker Ro¨schenthaler and Ulrich Kortz* Received 21st April 2012 DOI: 10.1039/c2cs35153f In the wide area of polyoxometalate (POM) chemistry, diphosphate/diphosphonate-based POMs represent a more recent area of study. However, in this short time it has emerged to become very dynamic, as shown by the wide variety of compounds reported. Ever since the discovery of the first polyoxotungstate framework constructed from diphosph(on)ate ligands, a widespread investigation on the preparative chemistry and properties of such compounds has followed. The main focus of such a study is based on factors such as the oxidation state of the metal, the effect of pH and temperature during synthesis, and the presence of different functional groups on the diphosphonate. In this review we discuss in detail all diphosphate/diphosphonate-based POMs, beginning with early developments, subsequent growth in interest, and finally focusing on the very latest developments.

1. Introduction Ever since the first report by Berzelius in 1826, the field of polyoxometalates (POMs) has seen tremendous growth in leaps and bounds, not only in the novelty and variety of compounds reported, but also in their many attractive properties ranging from catalysis to magnetism, leading to applications in therapeutics.1 Jacobs University–School of Engineering and Science, Bremen, Germany. E-mail: [email protected] w Part of a themed issue covering the latest developments in polyoxometalate science.

Abhishek Banerjee received his BSc degree in Chemistry from St. Xavier’s College, Calcutta in 2004, followed by an MS degree in Inorganic Solid State Chemistry from the Indian Institute of Science, Bangalore in 2007. He received his doctorate degree in Inorganic Chemistry, with distinction, under the supervision of Prof. Ulrich Kortz and Prof. Gerd-Volker Ro¨schenthaler from Jacobs University, Bremen in 2011. Abhishek Banerjee He is currently working as a post-doctoral fellow at Northwestern University, in the research group of Prof. Mercouri G. Kanatzidis. His current research interests include synthetic inorganic and solid-state chemistry, particularly in the areas of phosphonate and chalcogenide-based compounds.

7590

Chem. Soc. Rev., 2012, 41, 7590–7604

In such respect the structural characterization of POMs with diphosphate/diphosphonate groups is a relatively recent area of exploration, covering mainly the past two decades. Diphosphate/diphosphonate-based POMs predominantly have open-structures with the heterogroup(s) located on the outside of the polyanions, in sharp contrast to classical POMs usually containing encapsulated heterogroup(s). Such feature allows for subtle tuning of the POM structure and properties, for example by modifying the substituents on the diphosphonates. Diphosphonates, more colloquially referred to as bisphosphonates, are already well known as therapeutic drugs towards

Bassem S. Bassil was born in Beirut, Lebanon. He did his undergraduate studies at the American University of Beirut and graduated with a BS in Chemistry (1995–1999). In 2003 he moved to Germany for graduate studies at International University Bremen (now Jacobs University Bremen) and in 2005 he completed his MS in Nanomolecular Science. Then he pursued doctoral studies under the supervision of Prof. Bassem S. Bassil U. Kortz at Jacobs University in the area of transition metal containing polyoxotungstates (2005–2008). He received the DAAD prize for academic achievement and social involvement at Jacobs University in 2005. In 2008 he became a postdoctoral fellow in the research group of Prof. U. Kortz, and now holds a research associate position at Jacobs University. This journal is

c

The Royal Society of Chemistry 2012

bone-loss diseases, due to their general affinity towards calcium.2 In a similar sense several POMs have also been tested for potential uses in medicine over many years, the full potential of which is still to be realized.3 Combining diphosphonates with POMs thus carries a tremendous promise towards the design and development of novel and more efficient drug molecules to counteract the ever growing dangers of pathogens in the environment. Isopoly and heteropoly oxometalates have been studied for therapeutic use, and their application for specific purposes and needs has been investigated with respect to a modification of the addenda and hetero atoms, overall shape, size, charge, etc. Studies have been performed using POMs both in vitro and in vivo aimed at understanding their antibacterial and antiviral activity as well as their pharmacokinetics.4 The concurrent development of diphosphonates as therapeutic agents has occurred mainly along two different pathways and hence has been classified as such, depending on the type of functional group as well as the mode of action.5 Non-nitrogenous diphosphonates (e.g. etidronate, chlodronate, tiludronate) were the initial batch of compounds to be developed and studied6 with later developments mainly concerning nitrogenous diphosphonates (e.g. alendronate, risedronate, zoledronate) due to an increased potency towards curing such diseases.7 Thus the combination of diphosphates/ diphosphonates with POMs definitely holds tremendous potential towards the development of therapeutic agents for a variety of purposes. In this review, we will discuss the state of the art development of diphosphato/diphosphonato-POMs, with an emphasis mainly on their synthesis and structure. A detailed discussion is provided to correlate the structure of the POM obtained with the nature of the diphosphate/diphosphonate ligand, with a focus on the effect of the functional group of the diphosphonate on the POM structure.

Gerd-Volker Ro¨schenthaler was born in Bad Elster, Germany. He studied Chemistry at the University of Saarland, Saarbru¨cken, Germany, during 1963–1968, where he received the Dr rer. nat. degree in 1971. Then he moved to the Technical University of Braunschweig where he received his ‘‘Habilitation’’. He joined the Department of Chemistry, University of Bremen in 1978 until 2009. Since 2009 he is Professor of Chemistry at Gerd-Volker Ro¨schenthaler Jacobs University Bremen. He served as Visiting Professor at the Hebrew University of Jerusalem, and at the Israel Institute of Technology, Haifa, Israel, where he is Member of the Board of Governors. His group is active in synthetic organophosphorus and organofluorine chemistry.

This journal is

c


2. Polyoxometalates containing the diphosphate anion Initial results in the area of diphosphato/diphosphonato-POMs were obtained with the diphosphate anion, O3P–O–PO32 . It was observed that unlike the monophosphate PO43 , which is usually encapsulated inside the POM shell, the ditetrahedral diphosphate is ideally suited to obtain open POM architectures with its extended coordination capability. In the following sections we discuss all the POMs reported with the diphosphate ion. 2.1 Metals in their highest oxidation state Early works regarding the formation of polyanions with diphosphate-based tetrahedral groups consisted reports from Gibbs and Rosenheim.8 However detailed studies of the reaction of diphosphates with transition metals and their complete structural characterization were performed by Pope’s group and Himeno’s group. They were successful in obtaining the initial results of the reaction of diphosphate with W and Mo. Pope’s group was instrumental in the detailed study and structural characterization of many such compounds. Later, Burns and coworkers reported several polyoxouranates with diphosphate. In this section the development of the area along with the compounds obtained and characterized will be discussed. The most important point to be considered as we follow the development is the variation of the P–O–P bond angle with each subsequent structure reported, which we will state along with the respective structure in study. 2.1.1 Polyoxotungstates and -molybdates. The first example of a tungsto(VI)diphosphate was the polyanion [(P2O7)4WVI12O36]16 (WVI12POP4) having a unique dodecameric structure of a W12 assembly, with an open, saddle-shaped architecture, capped by

Ulrich Kortz studied Chemistry and Chemical Engineering in Giessen and Darmstadt (1982–1989), followed by doctoral studies at Georgetown University in Washington, DC (with Michael T. Pope, 1990–1995). Then he did a postdoc at Florence University, Italy (with Dante Gatteschi, 1995–1996), and another one at Versailles University, France (with Andre´ Te´ze´ and Gilbert Herve´, 1996–1997). He was Assistant Professor Ulrich Kortz (1997–2001) and then Associate Professor (2001–2002) at the American University of Beirut in Lebanon. In 2002 he joined the newly established International University Bremen (now Jacobs University) as Associate Professor, and in 2007 he was promoted to Full Professor. His current research interests include synthetic inorganic and organometallic chemistry, structural inorganic chemistry, polyoxometalate chemistry, hybrid organic–inorganic assemblies, catalysis, magnetism, and electrochemistry. Chem. Soc. Rev., 2012, 41, 7590–7604

7591

four diphosphate groups (P–O–P angle = 123.71).9 As emphasized earlier this structure was an unusual type of POM conformation with external hetero groups (Fig. 1a). The isostructural methylene-diphosphonate derivative [(O3PCH2PO3)4WVI12O36]16 (WVI12PCP4) was also obtained under similar synthetic conditions, albeit at a lower pH, and reported in the same article. The importance and subsequent emergence of the methylene-diphosphonate molecule as the ligand of choice in such systems will be discussed in the appropriate sections (vide infra). The two dodecameric polyanions WVI12POP4 and WVI12PCP4 were also the forerunners towards understanding the medicinal properties of such type of compounds, as both were shown to inhibit HIV-1 reverse transcriptase.10 Later Himeno and coworkers reported a 17-tungsto(VI)diphosphate, [(P2O7)WVI17O51]4 (WVI17POP), with an open ‘inkpotshaped’ structure comprising a {(P2O7)WVI16O50} fragment (P–O–P angle = 132.11) capped by a {WVIO5} squarepyramid (Fig. 1b).11 The structure of the first molybdo(VI)diphosphate, the 18-molybdodiphosphate [(P2O7)MoVI18O54]4 (MoVI18POP), was reported by Pope’s group.12a This polyanion was first reported by Himeno and coworkers and characterized by electrochemistry,

Fig. 1 Ball-and-stick representation of (a) the dodecameric [(O3P–X–PO3)4WVI12O36]16 (X = O, CH2) polyanion, and (b) the [(P2O7)WVI17O51]4 polyanion. Color code: W bluish-green, P magenta, O red, C gray.

7592

Chem. Soc. Rev., 2012, 41, 7590–7604

but these authors did not identify the molecular structure.12b Pope’s group was successful in structurally characterizing the polyanion revealing an 18-molybdo(VI)diphosphate assembly comprising two B-{PMo9} units connected by a diphosphate unit (Fig. 2a). This structure of MoVI18POP reveals some interesting features: (i) the P–O–P angle is almost linear (177.81) indicating significant p-bonding and an essentially sp-hybridized P–O–P oxygen atom; (ii) as a result the six oxygens connecting the two {PMo9} units are displaced towards the interior of the POM structure, leading to an hour-glass shape, whereas the classical Wells–Dawson phosphomolybdate [(PO4)2MoVI18O54]6 (Fig. 2b) has an ellipsoidal shape. Further Himeno and coworkers proposed a transformation of MoVI18POP, via the lacunary 15-molybdo(VI)diphosphate [H6(P2O7)MoVI15O48]4 (MoVI15POP),13 to the 12-molybdo(VI)diphosphate [H12(P2O7)MoVI12O42]4 (MoVI12POP),14 in an acidified MoO42 – P2O74 60% (v/v) CH3CN/H2O system. MoVI15POP was synthesized in an independent procedure by Himeno and coworkers,13 and later structurally characterized by Pope’s group. The structure of this polyanion was shown to be an extended version of MoVI18POP with the formula [{(P2O7)MoVI15O45}2]8 (MoVI30POP2), and can be viewed as a cigar-shaped assembly formed by fusing two trilacunary derivatives of the MoVI18POP parent structure.15 The single crystal XRD data of the tetra-butyl ammonium (TBA) salt revealed a co-crystallized [PMoVI12O40]3 Keggin ion. The clean product was isolated as an amorphous tetrapropyl ammonium (TPA) salt, as seen by 31P NMR spectroscopy. Such studies also suggested that the structurally still uncharacterized MoVI12POP is an oligomeric analogue of the dimeric MoVI30POP2, further supported by the observation that attempts to crystallize the MoVI12POP polyanion in acetonitrile always resulted in crystals of MoVI30POP2, indicating that in acetonitrile MoVI12POP easily breaks down to the 30-molybdo(VI)-2-diphosphate MoVI30POP2. Himeno and coworkers have also reported a mixed phosphate/selenite-diphosphate derivative of the MoVI30POP2, [(XO3)2(P2O7)MoVI30O90]8 (MoVI30POPX, X = HP, Se),16 making use of the previously obtained knowledge about the

Fig. 2 Ball-and-stick representation of (a) the polyanion [(P2O7)MoVI18O54]4 , (b) the standard Wells-Dawson polyanion [(PO4)2MoVI18O54]6 as a comparison. Note the change in shape resulting from the P–O–P bond. Color code: Mo bluish-green, P magenta, O red.

This journal is

c


coexistence of the MoVI15POP ion during the transformation process of the MoVI18POP to the MoVI12POP. The synthesis of MoVI30POPX (X = HP, Se) thus involves the formation reactions of Mo18POP and MoVI15POP and their subsequent transformation reactions. Crystals suitable for X-ray analysis were obtained only for the phosphate derivative,16a while the selenite derivative was characterized by IR and NMR spectroscopy.16b The structure of the MoVI30POPX (X = HP, Se) compound revealed a {(P2O7)MoVI12O42} fragment, derived from the MoVI18POP structure after removal of two {MoVI3O13} caps, and then capped on each side by a B-type {(HPO3)MoVI9O24} unit. Thus the proposed formation mechanism shows the in situ formation of the 12-molybdo(VI)diphosphate, and then subsequent fusion on either side of two B-XMo9 units, [H6(XO3)MoVI9O30]2 (X = HP, Se).16b Another interesting structure of a molybdo(VI)diphosphate is the 6-molybdo(VI)diphosphate [(P2O7)MoVI6O18(H2O)4]4 (MoVI6POP) composed of a six-membered ring of MoO6 octahedra, capped by the diphosphate group (P–O–P angle = 112.81), which was reported by Kortz.17 2.1.2 Polyoxouranates. The literature on urano(VI)diphosphate is still very recent, so far contributed solely by Burns and coworkers. Such polyanion structures, reported during the last couple of years and synthesized using conventional aqueous phase synthetic procedures, are constructed of U6+ cations in pentagonal or hexagonal bipyramidal coordination capped by the oxygen atoms of the uranyl ion, with each polyhedron connected to a neighbor via edge-sharing by means of a peroxide group and further coordinated by oxygen atoms of diphosphate groups.18 Of all the structures reported the largest polyanion is formulated as [(UVIO2)45(O2)44(P2O7)23]90 (UVI45POP23) and has a highly complex distorted dumbbell shape (Fig. 3).18b Several other interesting structures have also been reported, such as two U30 clusters, namely the [(UVIO2)30(O2)30(P2O7)12(PO4)(H2O)5]51 (UVI30POP12P1),18a consisting of two U15 units made up of similar 7 or 8 coordinate uranyl polyhedra capped by diphosphate groups, connected by two diphosphate units and in excess a phosphate group disordered over two positions, and the [(UVIO2)30(O2)39(P2O7)6]42 (UVI30POP6) with 18 uranyl triperoxide hexagonal bipyramids, 12 uranyl diperoxide hexagonal bipyramids, and six diphosphate groups.18c In the next category of compounds each consists of twenty uranium atoms, [(UVIO2)20(O2)24(P2O7)6]32 (UVI20POP6a) and [(UVIO2)20(O2)24(P2O7)6]32 (UVI20POP6b), differing only in the arrangement of the diphosphate groups, as well as [(UVIO2)20(O2)20(P2O7)10]40 (UVI20POP10). For the cluster with 26 uranium atoms, namely [(UVIO2)26(O2)33(P2O7)6]38 (UVI26POP6) and [(UVIO2)26(O2)28(P2O7)11]48 (UVI26POP11), 6 and 11 diphosphate units, respectively, provide linkages between the hexagonal bipyramids of uranium. Other polyoxouranates with diphosphate include (UVI20POP10), [(UVIO2)24[(UVIO2)20(O2)20(P2O7)10]40 48 VI VI (O2)24(P2O7)12] (U 24POP12), [(U O2)32(O2)32(P2O7)16]64 VI (U 32POP16), and [(UVIO2)42(O2)42(OH)36(P2O7)3]48 VI (U 42POP3). 2.2

Mixed-valent and fully reduced polyoxometalates

The first reported diphosphato-POM with all metal centers in a reduced oxidation state was the tetravanadyl(IV) polyanion This journal is

c


Fig. 3 Polyhedral representation of the polyanion [(UVIO2)45(O2)44(P2O7)23]90 (UVI45POP23).

[(VIVO)4(P2O7)2(OCH3)4]4 {(VIVO)4POP2Met2},19a consisting of a cyclic assembly of four {VIVO} units connected by two diphosphate and four methoxy groups, which was synthesized in an organic medium. Recently, Cummins and coworkers reported the synthesis in an aqueous medium of the structurally analogous vanado(IV)diphosphate compound [(VIVO)4(P2O7)4(H2O)4]8 {(VIVO)4POP4} where the four {VIVO} units are connected by a diphosphate group, leading to a cyclic assembly.19b However, in the latter structure three of the {VIVO5} units point outwards and the remaining vanadyl unit points inwards to the polyanion core, in contrast to the methoxy analogue, where all four vanadyl groups point outwards. Later on, Mialane, Dolbecq, and coworkers were successful in synthesizing the first fully reduced molybdo(V)diphosphate.20 The polyanion [(MoV2O4)10(P2O7)10(CH3COO)8(H2O)4]28 {(MoV2)10POP10Acet8} has a bicyclic structure of ten {MoV2O4} units connected by ten diphosphate groups, eight of these ten units being capped on the inside by acetate ligands (Fig. 4). The formate derivative of (MoV2)10POP10Acet8, [(MoV2O4)10(P2O7)10(HCOO)10]30 {(MoV2)10POP10Form10}, having all ten {MoV2O4} units capped from the inside by the carboxylate groups, was reported a year later by Zhang and coworkers.21 2.3 Keggin-type polyoxotungstates Apart from the above mentioned derivatives, Peng and coworkers have reported several derivatives based on the monolacunary tungstosilicate Keggin ion [SiW11O39]8 with grafted transition metal diphosphate units.22 In the absence of single crystals no direct structural elucidations were possible for such compounds, and they were hence characterized by electrochemical, infrared, and NMR studies. The complexes were formulated as [SiW11O39M(H3P2O7)]7 (SiW11MPOP M = MnII, CoII, NiII, and ZnII) based on elemental analysis results, and their structure was suggested to be an {M(H3P2O7)} fragment grafted at the lacunary site of {SiW11}. Chem. Soc. Rev., 2012, 41, 7590–7604

7593

(VIVO2Etid3) consists of a trimeric assembly of three {VIVO6} octahedra connected by diphosphonate groups.27 The structure solution shows extensive disorders with respect to the metal and ligand positions as well as coordination sites, and the optimized model obtained had a 0.67 : 0.33 disorder ratio. Interestingly, the hydroxyl group on the diphosphonate does not participate in metal bonding. This structural characteristic of several diphosphonato-POMs will be discussed in detail in Section 3.2.2. 3.2 Polyoxomolybdates

Fig. 4 Combined ball-and-stick/polyhedral representation of [(MoV2O4)10(O3P–X–PO3)10(CH3COO)8(H2O)4]28 (X = O, CH2). Color code: MoVO6 turquoise octahedra, PO3C magenta tetrahedra, C gray, H white.

Electrophoretic studies showed the incorporation of the transition metal into the monolacunary polyanion, with 31P and 183W NMR studies furnishing data to corroborate the suggested structure. Further single-crystal X-ray studies are, however, necessary in order to verify this unusual structuretype, with NMR data not convincing enough for accurate structural determination.

3. Polyoxometalates based on diphosphonates The principal disadvantage as well as impediment towards further exploration of the diphosphate chemistry in forming several more polyanionic structures is its tendency to hydrolyze in acidic solutions. Due to this fact, more relevant effort was made to incorporate the relatively robust methylenediphosphonate anion into such systems. The ease of incorporating several functional groups into the central methylene can also open the way towards obtaining structures with tailor-made properties.23 The following sections are devoted to polyanions obtained with methylene-diphosphonate and its derivatives. 3.1

Polyoxovanadates

All the molecular polyoxovanadates with methylenediphosphonate reported so far have been synthesized using hydrothermal techniques and isolated as insoluble products. Monovanadyl(IV)diphosphonate [VIVO{HO3PCH2PO3H}2(H2O)]2 {VIVO(PCPH2)2} cannot technically be termed as a POM.24 Conventional polyoxovanadate structures include the acetylacetonato derivative [(VIVO)2(CH3COCHCOCH3)2– {O3PCH2PO3}]2 {(VIVO)2acacPCP}, which comprises two {VIVO(acac)} units connected by methylene-diphosphonate,25 and the oxyfluoride complex [VIV2VIIIO2F6{O3PCH2PO3}2]7 (VIV2VIIIO2F6PCP2), consisting of a central {VIIIO4trans-F2} unit linked via bridging fluorides to {VIVO4cis-F2} and methylenediphosphonate.26 The only polyoxovanadate structure with a substituted diphosphonate was reported by Sergienko and coworkers in 2001. The polyoxovanado(IV)diphosphonate [(VIVO2)3{HO3P–C(OH)(CH3)–PO3}3]0.67[{VIVO(OH)}3{O3P–C(OH)(CH3)–PO3}3]0.33 7594

Chem. Soc. Rev., 2012, 41, 7590–7604

Molybdenum, being the second most common element for the construction of POMs after tungsten, has also been studied extensively towards the formation of several diphosphonatebased polyanions. Unlike tungsten, which prefers to remain in the highest oxidation state of +6, molybdenum can potentially undergo a reduction to a lower oxidation state of +5 under suitable conditions. Such oxidation number versatility leads to the formation of new types of polyanion structures, be it mixed-valent or completely reduced. The following discussion presents all such diphosphonate-based polyoxomolybdates. 3.2.1 Structures with methylene-diphosphonate. The incorporation of methylene-diphosphonate is driven mainly by its robustness in various magnitudes of pH. Interestingly, the only polyoxomolybdate(VI) structure obtained with methylenediphosphonate is the [(O3P–CH2–PO3)MoVI6O18(H2O)4]4 (MoVI6PCP),28 isostructural with the diphosphate derivative MoVI6POP, previously mentioned in Section 2.1.1.17 In continuation of their work on diphosphate, Mialane, Dolbecq, and coworkers reported several isostructural molybdo(V)diphosphonate derivatives with methylene-diphosphonate. Examples include [(MoV2O4)10(O3P–CH2–PO3)10(CH3COO)8(H2O)4]28 {(MoV2)10PCP10Acet8} and [(MoV2O4)10(O3P– CH2–PO3)10(HCOO)10]30 {(MoV2)10PCP10Form10},29 isostructural with (MoV2)10POP10Acet8 and (MoV2)10POP10Form10, respectively. Kortz and coworkers have prepared similar derivatives with ethylidene-diphosphonate {H2CQC(PO3H2)2}, [(MoV2O4)10{H2CQC(PO3)2}10(CH3COO)8(H2O)4]28 {(MoV2)10PEP10Acet8}, and [(MoV2O4)10{H2CQC(PO3)2}10(HCOO)10]30 {(MoV2)10PEP10Form10}, which has shown the possibility of formation of simple polyanion structures alongside the change in hybridization of the central carbon-atom in methylenediphosphonate.30 The first of a series of unique mixed-valent and fully reduced molybdo(V/VI)diphosphonates was reported by Sevov and coworkers in 2002. The mixed-valent [(MoV2O4)3(MoVIO4)(O3P–CH2–PO3)3]8 {MoVI(MoV2)3PCP3} was synthesized hydrothermally, and isolated as an insoluble salt of piperazinium and ethylenediammonium.31 Later Mialane, Dolbecq, and coworkers reported the soluble sodium-salt analogue in 2004, synthesized by an independent procedure.29 The triangular-shaped assembly of the polyanion is constructed from three {MoV2O4} units acting as edges of the triangle, connected with each other by methylene-diphosphonate, and capped from the inside by a tetrahedral {MoVIO4} unit, resulting in the mixed-valency. They also reported two years later the fully reduced methyl arsonate analogue, This journal is

c


[(MoV2O4)3(O3P–CH2–PO3)3(CH3AsO3)]8 {(MoV2)3PCP3(MeAs)}, where the {CH3AsO3} group replaces the central {MoVIO4} tetrahedron.32 The tetrameric mixed-valent [(MoVIO3)2(MoV2O4)2{O3P–CH2–PO3}2{HO3P–CH2–PO3}2]10 {MoVI2(MoV2)2PCP2(PCPH)2} was also reported alongside. This polyanion has a square-shaped structure made from two {MoV2O4} units bridged by two corner-sharing {MoVIO6} octahedra and capped by four diphosphonates in the corners.32 Several examples of fully reduced polyoxomolybdates(V) with methylene-diphosphonate were also reported by the same group. The first to be reported was the polyanion [(MoV2O4)4(O3P–CH2–PO3)4(XO3)2}]12 (X = C, S) {(MoV2)2PCP4X} with carbonate29 and sulfite capping groups.32 The structure of the polyanion consists of two tetrameric {(MoV2O4)2(O3P–CH2–PO3)} assemblies, connected via one m3-O and two m2-O atoms coming from the capping Z3-XO32 (X = C, S) group, and linked by two diphosphonate ligands. An isostructural mono-protonated and methylene-diphosphonate-capped derivative, [(MoV2O4)4(O3P–CH2–PO3)4(O3P–CH2–PO3H)2]14 {(MoV2)4PCP4(PCPH)2}, was also reported.32 Another molybdo(V)diphosphonate, the cyclic [{MoV2O4}6(OH)6{O3P–CH2–PO3}6]18 {(MoV2)6PCP6}, consists of a hexameric assembly of {MoV2O4} units connected by methylene-diphosphonate.33 Interestingly this assembly resembles the chair conformation of cyclohexane with methylenediphosphonate ligands at the vertices and {MoV2O4} units at the edges. 3.2.2 Polyanions obtained with methylene-diphosphonate derivatives. The ease of incorporating functional groups onto the central carbon atom of methylene-diphosphonate has paved the way towards further exploration in diphosphonatecontaining POMs.23 Upon careful examination of recent studies where diphosphonates were used for therapeutic purposes, it is observed that all such compounds contain an OH group at the PCP carbon atom, which mainly influences the chemical properties and pharmacokinetics.34 In POM synthesis, the use of such diphosphonates can greatly influence many properties of the polyanion, such as structure and solution stability. Herein we will discuss such polyanions containing functionalized methylene-diphosphonate. Sergienko and coworkers were the first to examine the reactivity of tungstates and molybdates with the simple diphosphonic acid or etidronic acid. In such an investigation several simple anionic species were reported with molybdates, such as [MoVIO2{O3P–C(O)(CH3)–PO3}2]8 , [MoVI2O6{O3P–C(O)(CH3)–PO3}]5 , and [MoVI3O9{O3P–C(O)(CH3)–PO3}]5 .35 The dimeric S-shaped polyanion [MoVI6O17{O3P–C(O)(CH3)–PO3}2]8 (MoVI6Etid2), composed of two [MoVI3O9{O3P–C(O)(CH3)–PO3}]5 monomers is the closest to be assigned as a POM.36 Subsequent development with reduced molybdates was done by Mialane, Dolbecq, and coworkers who reported the first series of compounds in 2010.37 The planar polyanion [(MoV2O4)2{O3P–C(O)(CH3)–PO3}2]6 {(MoV2)2Etid2} is an aggregrate of two {MoV2O4} units capped by the diphosphonate units, where the two phosphonate groups are inequally bonded to each unit (PO(OMo)2 vs. PO(OMo)(OH)). For this This journal is

c


acyclic polyanion, formation of C–O–Mo bonds and prolonged solution stability were observed. The chair-shaped cyclic [{MoV2O4}6(OH)6{O3P–C(OH)(CH3)–PO36]18 assembly {(MoV2)6HEtid6} is isostructural with {(MoV2)6PCP6}, discussed in Section 3.2.1. A heptameric cyclic structure with the polyanion [{MoV2O4}7{O3P–C(OH)(CH3)–PO3}7(CH3COO)7]21 {(MoV2)7HEtid7Acet7}, consisting of seven {MoV2O4} pairs capped by acetate groups in planar geometry, was also reported in the same article. Interestingly, both such polyanions have the hydroxyl group in the terminal position, and proved to be unstable in solution. Isostructural derivatives of {(MoV2)2Etid2}, namely [{MoV4O8}{O3P–C(O)(C3H6NH3)– PO3}2]4 {(MoV2)2Alen2} with alendronate and [{MoV4O8}{O3P–C(O)(C10H14NO)–PO3}2]6 {(MoV2)2PhAlen2} with aminophenyl-alendronate, were also reported later by the same group in 2011.38 Another mixed-valent molybdo(V/VI)diphosphonate with etidronic acid [(MoVIO3)2(MoV2O4)2{O 3 P–C(OH)(CH 3)–PO 3} 2 {O 3P–C(OH)(CH 3 )–PO 3 H} 2] 10 {MoVI2(MoV2)2HEtid2(HEtidH)2}, reported very recently by Kortz and coworkers,39 is isostructural with {MoVI2(MoV2)2PCP2(PCPH)2}. Wang and coworkers reported another mixed-valent polyoxomolybdate based on etidronate, [(MoV2O4)(MoVI2O6)2{O3P–C(O)(CH3)–PO3}2]8 {(a-MoVI2)2(MoV2)Etid2}. This polyanion has a C-shaped structure constructed from a single {MoV2O4} unit joined on either side by two {MoVI2O6} dimers by two fully deprotonated diphosphonates.40 The analogous alendronate derivative, [(MoV2O4)(MoVI2O6){O3P–C(O)(C3H6NH3)–PO3}2]6 {(a-MoVI2)2(MoV2)Alen2}, was reported a year later concurrently by the group of Mialane and Dolbecq, and the group of Wang.38,41 Notably, the Wang group was successful in resolving the optical isomers of the alendronate derivative in the solid state, made possible due to a restriction by the crystal lattice of the ‘‘folding’’ alkyls, inducing a chirality that otherwise cannot be observed in solution (Fig. 5 top). Kortz and coworkers also reported recently the analogous risedronate [{MoVI2O6}2{MoV2O4}{O3P–C(O)(CH2-3-C5NH4)-PO3}2]8 {(a-MoVI2)2(MoV2)Risd2} and 3-(4-pyridyl)-1-hydroxy ethylidene-1,1-diphosphonate [{MoVI2O6}2{MoV2O4}{O3P–C(O)(CH2-4-C5NH4)-PO3}2]8 {(a-MoVI2)2(MoV2)(4-PyrPC2OP)2} derivatives, with the location of the nitrogen-atom in the aromatic ring having a marked influence upon the orientation of the rings in the solidstate (Fig. 5a and b).42 The same group successfully incorporated fluorine into the organic framework of molybdo-diphosphonates, using them as scaffolds. Fluorine atom, due to its uniqueness in small size and high electronegativity, has found many applications in medicine, materials science, catalysis etc.43 and is expected to have significant effects on the structure and properties of such compounds. The significant influence of the fluorine groups on the deprotonation of the hydroxyl group and formation of C–O–Mo bonds was observed for the first time in cyclic polyoxomolybdate-diphosphonate chemistry. Two new cyclic polyanions with F3-etidronic acid were prepared. The mixed-valent [(MoVI2O5)2(MoV2O4)2{O3P–C(O)(CF3)–PO3}4(CH3COO)2]14 {(b-MoVI2)2(MoV2)2F3-Etid4Acet4} has an ellipsoidal shape made of two pairs of edge-sharing {MoV2O4} and cornersharing {MoVI2O5} units connected alternatively by four fully Chem. Soc. Rev., 2012, 41, 7590–7604

7595

Fig. 5 Top: Ball-and-stick representation of the two optical isomers of [(MoV2O4)(MoVI2O6){O3P–C(O)(C3H6NH3)–PO3}2]6 . Bottom: combined ball-and-stick/polyhedral representation of (a) [(MoV2O4)(MoVI2O6){O3P–C(O)(CH2-3-C5NH4)–PO3}2]8 , and (b) [(MoV2O4)(MoVI2O6){O3P–C(O)(CH2-4-C5NH4)–PO3}2]8 (note the change in orientation of the aromatic rings w.r.t. the shift in the position of the N-atom). Color code: MoVI bluish-green, MoV turquoise, MoVO6 turquoise octahedra, P magenta, O red, C gray, N blue, H white.

deprotonated diphosphonate groups.39 The fully reduced polyanion [{MoV2O4(H2O)}4{O3P–C(O)(CF3)–PO3}4]12 {(MoV2)4F3Etid4} is constructed of four {MoV2O4(H2O)}4 units connected by four fully deprotonated diphosphonate groups (Fig. 6).44 Isostructural derivatives with risedronic acid and alendronic acid,

Fig. 6 Combined ball-and-stick/polyhedral representation of the cyclic tetramer of [{MoV2O4(H2O)}4{O3P–C(O)(CF3)–PO3}4]12 . Color code: MoVO6 turquoise octahedra, P magenta, O red, C gray, F yellow.

7596

Chem. Soc. Rev., 2012, 41, 7590–7604

[{MoV2O4(H2O)}4{O3P–C(O)(CH2-3-C5NH4)–PO3}4]12 {(MoV2)4Risd4}42 and [{MoV2O4(H2O)}4{O3P–C(O)(C3H6NH3)–PO3}4]8 {(MoV2)4Alen4},38 were also reported later. Among other polyoxomolybdates with alendronic acid, the dimeric and tetrameric assemblies of the monomeric unit [(MoVIO3)(MoVI2O6){O3P–C(O)(C3H6NH3)–PO3}]4 have been extensively studied. The monomeric unit is built from face-sharing {MoVI2O6} dimers that share a vertex with monomeric {MoVIO6} octahedra. The dimeric species, formulated as [(MoVI2O5)(MoVI2O6)2{O3P–C(O)(C3H6NH3)–PO3}2]6 {(a-MoVI2)2(b-MoVI2)Alen2} was obtained as a co-crystallized racemic mixture by the group of Wang,45 and was observed later by the group of Mialane and Dolbecq to form several conformational isomers with different substituents. The A-type conformation possessing a C2h symmetry was obtained for the polyanions A-[(MoVI2O5)(MoVI2O6)2{O3P–C(O)(C3H6NH3)– PO3}2]6 {A-(a-MoVI2)2(b-MoVI2)Alen2}, A-[(MoVI2O5)VI 6 (Mo 2O6)2{O3P–C(O)(C3H6N(CH3)2H)–PO3}2] {A-(a-MoVI2)2(b-MoVI2)(Me2Alen)2}, and A-[(MoVI2O5)(MoVI2O6)2{O3P– C(O)(C4H8NH3)–PO3}2]6 {A-(a-MoVI2)2(b-MoVI2)(PAHC5P)2} with alendronate, the dimethyl derivative of alendronate, and 5-amino-1-hydroxy-pentenyl-1,1-diphosphonate, respectively. The B-type conformation has the two trimeric units twisted along two perpendicular planes possessing the approximate symmetry of C1, and was observed for the polyanions B-[(MoVI2O5)(MoVI2O6)2{O3P–C(O)(C3H6NH3)–PO3}2]6 {B-(a-MoVI2)2VI VI VI (b-Mo 2)Alen2} and B-[(Mo 2O5)(Mo 2O6)2{O3P–C(O)(C3H6N(CH3)H2)–PO3}2]6 {B-(a-MoVI2)2(b-MoVI2)MeAlen2} with alendronate and monomethylated alendronate, respectively.46 The tetrameric polyanion with alendronic acid was formulated as [(MoVI3O8)4{O3P–C(O)(C3H6NH3)–PO3}4]8 {(MoVI3)4Alen4} and observed to adopt a cyclic geometry.38,45,47 The two isostructural [(MoVI3O8)4{O3P–C(O)(C3H6N(CH3)H2)–PO3}4]8 {(MoVI3)4MeAlen4} and [(MoVI3O8)4{O3P–C(O)(C3H6N(CH3)2H)–PO3}4]8 {(MoVI3)4(Me2Alen)4} polyanions with mono- and dimethylated alendronate derivatives were also reported later by the same group.46 Another mixed-valent polyoxomolybdate with risedronic acid, [{MoV2O4}{MoVIO3}2{HO3P–C(O)(CH2-3-C5NH4)–PO3}2]6 {MoVI2(MoV2)Risd2}, was reported by Kortz’s group very recently and has an open-shell structure consisting of the dinuclear {MoV2O4} unit capped by {MoVIO3} groups on either side and stabilized by the diphosphonate groups.42 With unequal deprotonation of the phosphonate groups on each of the diphosphonates, the phosphorous atoms were observed to be chemically and magnetically inequivalent by 31P solution NMR. Derivatives of molybdo-diphosphonates with transition metals and lanthanides have been reported very recently. The transition metal-containing molybdo(V)etidronates are formulated as [M{MoVI2O6CH3C(O)(PO3)2}2Hx]n {M(a-MoVI2)2Etid2}, where M = FeIII, n = 7, x = 0; CrIII, n = 5, x = 2; MnII, n = 8, x = 0.48 The isostructural polyanions consist of two [(MoVI2O6){O3PCH3C(O)PO3}]10 units linked by a transition metal. Isostructural lanthanide-derivatives of molybdo(V)etidronates, [Ln5(MoVI3O8){O3PC(O)(CH3)PO3}6]3 (Ln5MoVI3Etid6), where Ln = CeIII, PrIII, NdIII, SmIII, EuIII, GdIII, TbIII, have a triangular assembly of three ((Mo3O8){O3PC(O)(CH3)PO3}3) trimers, capped by lanthanide-cations.49 This journal is

c


Fig. 8 Ball-and-stick representation of the one-dimensional chain [{O3PCH(NMe2)PO3}W2O6]4 N. Color code: W bluish-green, P magenta, O red, N blue, C gray.

Fig. 7 Ball-and-stick representation of the mixed metal cantilever complex [VIV{MoVI2O6}{O3P–C(O)(C3H6NH3)–PO3}2]4 . Inset shows [MVI6O17{O3P–C(O)(CH3)–PO3}2]8 (M=Mo, W) for structural comparison. Color code: MoVI bluish-green, VIV green, MoVO6 turquoise octahedra, P magenta, O red, C gray, N blue, H white.

Finally, Wang and coworkers have reported the first mixedmetal polyoxomolybdate-vanadate with etidronic and alendronic acid, namely [VIV{MoVI2O6}{O3P–C(O)(CH3)–PO3}2]6 IV VI {V (a-Mo 2)Etid2} and [VIV{MoVI2O6}{O3P–C(O)(C3H6NH3)– PO3}2]4 {VIV(a-MoVI2)Alen2} (Fig. 7).50 These two isostructural compounds exhibit an ‘S’-shaped architecture consisting of two {MoVI2O6} units connected by a {VIVO6} octahedron, with the diphosphonate ligands grafted on the side and having their alkyl groups in a cantilever-type arrangement. These structures show similarity with the {MoVI6Etid2} polyanion discussed earlier in the same section, with the central {MoVI2O7} unit being replaced by the {VIVO6} octahedron.36 3.3

Polyoxotungstates

So far the only polyoxotungstate reported with methylenediphosphonate is the dodecameric assembly [(O3P–CH2–PO3)4W12O36]16 (WVI12PCP4, Fig. 1a),9 isostructural with the diphosphate derivative WVI12POP4. The first report of a polyoxotungstate (and POM) containing a functionalized diphosphonate was by Pope’s group. The solid state structure of polyanion [{O3P–CH(NMe2)–PO3}W2O6]4 (1D-WVIPCNMe2P) consists of a 1-D chain of monomeric units, each made of two corner-linked {WO4} tetrahedra bridged by diphosphonates, with the hetero groups alternating up and down (Fig. 8).51 As a result of their extensive studies on the reactivity of tungstates with etidronic acid, Sergienko and coworkers have reported several simple monomeric and dimeric structures, such as [WVIO3{O3P–C(O)(CH3)–PO3}]5 and [WVI2O6{O3P–C(O)(CH3)–PO3}2]5 .52 However, the compound [WVI6O17{O3P–C(O)(CH3)–PO3}2]8 (WVI6Etid2),53 possessing an S-shaped structure (Fig. 5a) and isostructural with the molybdate derivative (MoVI6Etid2),37 is the only candidate that can be technically labeled as a polyanion. Very recently Mialane, Dolbecq, and coworkers have reported an alendronate-based {CoII3} cluster with a trilacunary tungsto-phosphate Keggin, [(B-a-PW9O34)CoII3(OH)(H2O)2{O3PC(O)(C3H6NH3)PO3}2CoII]14 .54 The structure of this This journal is

c


polyanion is composed of two {B-a-PW9O34CoII3} subunits related by a pseudo inversion center. The subunits are connected by a central CoII, located at the inversion center, and two alendronate groups. 3.4 Polyoxouranates Besides the report of several structures with the diphosphonate anion, Burns and coworkers have recently reported uranylbased POM structures with either pure methylene-diphosphonate or mixed diphosphate/methylene-diphosphonate.18c Similar to the pure diphosphate-based polyoxouranates discussed in Section 2.1.2, such compounds are constructed from edgeshared UVIOx polyhedra which are 7- or 8-coordinated by methylene-diphosphonate groups. So far only one pure methylene-diphosphonate derivative has been reported, having the formula [(UVIO2)24(O2)24(O3P–CH2–PO3)12]48 (U24PCP12) and isostructural with the diphosphate derivative (U24POP12).18a The mixed [(UVIO2)24(O2)24(P2O7)12]48 diphosphate/diphosphonate derivative has the formula [(UVIO2)18(O2)18(OH)2(O3P–CH2–PO3)6(P2O7)2]34 (U18PCP6POP2), where the diphosphate anions are located in the central region and the methylene-diphosphonates connect the top and bottom portions of the cluster.18a

4. Coordination polymers constructed with diphosphonates Besides the area of conventional POMs, the literature of diphosphonate-containing compounds also encompasses several inorganic coordination polymers, mainly with the metal vanadium and very recently with ruthenium and several actinides. 4.1 Vanado-diphosphonates Since the report of the first vanado-diphosphonate compound by Jacobson and coworkers in 1990, the literature of such species has observed a tremendous increase in the number of publications from different research groups, mainly the ones of Zubieta, Fe´rey, and Jacobson. Due to the ability of vanadium to have coordination numbers of 4, 5, and 6 as well as oxidation states of +3, +4, and +5, the structural variety of such vanado-diphosphonates is immense. A close examination of the chemistry of vanadium reveals that V(IV) and V(V) tend to adopt tetrahedral, square-pyramidal, trigonalbipyramidal, or octahedral geometries, while V(III) characteristically tends to assume octahedral geometry. Hence together Chem. Soc. Rev., 2012, 41, 7590–7604

7597

with the tetrahedral coordination of the phosphonate groups such structures are observed to possess characteristics of very well-known framework compounds, such as aluminophosphates and silicates.55 This section will try to cover all such vanadate structures reported till date with methylenediphosphonate and higher alkylphosphonate analogues, with a focus on the structural assembly and the role of the phosphonate ligand in such assemblies. 4.1.1 Vanado-diphosphonates based on one-/two-/threedimensional V–P–X (X = O and/or F) assemblies. A closer look into the structural diversity of vanado-diphosphonates reveals that many such structures possess infinite metal-phosphonate-oxo/ fluoro linkages. The phosphonate-alkyl chain is then observed to connect such assemblies with each other leading to either two-dimensional sheets or three-dimensional frameworks. Another common feature among such a class of compounds is the presence of two or more carbons on the alkyl-chains of the diphosphonate, reducing electrostatic repulsion between the layers. The first of such types of structures was reported in 1995 by Zubieta and coworkers. Examples of compounds having one-dimensional V–P–O assemblies include [(VIVO){O3P(CH2)2PO3}]2 (2D-VIVOPC2P) and [(VIVO)2{O3P(CH2)3PO3H}2]2 {2D-(VIVO)2(PC3PH)2}, with ethylene-diphosphonate and propylene-diphosphonate. Chains of 2D-VIVOPC2P are constructed from square-pyramidal {VIVO5} groups cornershared with two phosphonate tetrahedra (Fig. 9a).56 As for 2D-(VIVO)2(PC3PH)2, alternate {VIVO5} square-pyramidal groups connect with the phosphonate tetrahedra to form the 1-D double chain (Fig. 9b).57 In the latter structure one of the phosphonate ligands exhibits pendant PQO and P–OH groups and hence does not participate in further connectivity or propagation of the structure. The analogous ethylene-, butylene-, and hexylene- derivatives, [(VIVO)2{O3P(CH2)nPO3H}2]2 {2D-(VIVO)2(PCnPH)2, n = 2, 4, 6}, were also reported by Zubieta and coworkers in 2006.58 The alkyl chains connect these one-dimensional assemblies to form two-dimensional sheets. The counter-cations of the anionic assemblies, ethylenediammonium for 2D-VIVOPC2P and piperazinium for 2D-(VIVO)2(PCnPH)2, respectively, are observed to occupy the inter-lamellar region. The first examples of two-dimensional V–P–O assemblies are the compounds [VIII3{O3P(CH2)2PO3}{HO3P(CH2)2PO3H}3] {3D-VIIIPC2P(PC2PH2)3} and [(VIIIO)VIV2(OH)2{O3P(CH2)2PO3}]2 (3D-VIIIVIV2PC2P) obtained in the same product mixture and separated manually.59 The oxidation state of +3 for vanadium has been rarely observed in conventional polyoxovanadate chemistry.60 The structure of 3D-VIIIPC2P(PC2PH2)3 reveals the presence of two different types of phosphonate groups. One group coordinates to each of the three adjacent vanadium atoms, while the other bridges two adjacent vanadium atoms within a layer, resulting in a pendant protonated P–OH unit. Each vanadium atom bridges through two symmetrical {V–O–P–O–V} connectivities to each of the four adjacent vanadium centers to produce the two-dimensional layer motif (Fig. 9c). For the mixed-valent 3D-VIIIVIV2PC2P the structure consists of both octahedral V(III) and square-pyramidal V(IV) centers. The overall two-dimensional 7598

Chem. Soc. Rev., 2012, 41, 7590–7604

assembly is observed to consist of linear chains of the dimeric unit {VIV2O2(OH)2} formed from corner-shared {VIVO4} polyhedra. These units are capped by phosphonate groups and further connect via corner-sharing {VIIIO6} octahedra (Fig. 9d). Similar phosphonate-capped and corner-sharing {V2O2(OH)2} dimers have also been reported with other vanado-diphosphonate structures. For [(VIVO)2(OH)(H2O){O3P(CH2)3PO3}] {3D(VIVO)2PC3P}, the slightly modified binuclear motif [VIV2O2(OH)], with VIV atoms in square-pyramidal coordination, directly connects with other such dimeric units through the free phosphonate groups to form 5- and 8-membered rings in the two-dimensional layer (Fig. 9e).56,61,62 Furthermore, Fe´rey and coworkers showed the transformation of this compound from the mono-valent to the mixed-valent variant, [VVVIVO3(H2O){O3P(CH2)3PO3}] (3D-VVVIVPC3P), by changing the temperature of synthesis. The mixed-valent species was obtained at 443 K and the monovalent one at 473 K.61,62 Such a transformation occurs due to the protonation of one of the terminal oxygens at the vanadium centers. The mono-valent pentylene derivative, [(VIVO)2(OH)2(H2O){O3P(CH2)5PO3}2]2 {3D-(VIVO)2(PC5P)2}, of the same structure type was also reported later by Zubieta and coworkers,58 which showed a transformation from the three-dimensional structure to a bilayer when increasing the chain length of the diphosphonate from three to five. This transformation is a result of the change in the orientation of the phosphonate groups in each diphosphonate ligands from the anti-orientation in the butylene derivative to the syn-orientation in the pentylene derivative. A similar bilayer arrangement of [VIV2O2(OH)] dimers was also observed for [(VIVO)2(OH){O3P(CH2)2PO3}] {3D-(VIVO)2PC2P}, where the dimers are also extensively connected by the phosphonate groups, however with slightly smaller apertures (Fig. 9f).63 A different type of dimeric unit, consisting of face-sharing octahedra and formulated as {V2O8(OH)}, has also been observed in several vanado-diphosphonate structures. The first of such compounds is the mixed-valent [VIVVVO2(OH){O3P(CH2)2PO3}] (3D-VIVVVPC2P), which was reported in 1998 by Fe´rey and coworkers, and consists of the {VIVVVO8(OH)} dimer connected in chains by phosphonate groups with an alternate up–down arrangement (Fig. 9g).64 Each phosphonate group links three {V2O8(OH)} units of a layer with three oxygen atoms, two are terminally bound to two vanadium sites of adjacent binuclear units and the third bridges the vanadium octahedra of a single binuclear unit. The analogous monovalent structure with propylene-diphosphonate, [(VIVO)2(H2O){O3P(CH2)3PO3}] {3D-(VIVO)2PC3P}, was also reported by Fe´rey and coworkers in 2000.65 An extensive series of compounds [(VIVO)2(H2O){O3P(CH2)nPO3}] {3D-(VIVO)2PCnP, n = 2–5} based on the same structure-type was later reported by Zubieta and coworkers with ethylene, propylene, butylene, and pentylene-diphosphonates. The expansion of the alkyl chain in these compounds is reflected not only in the interlamellar separation but also in the accessible void volume to solvent molecules.58 Vanado-diphosphonate structures, built from extensive V–P–O assemblies, have also been found without the presence of any dimeric units. Such compounds include the mixed-valent This journal is

c


Fig. 9 Figure illustrates the different types of V–P–O layers obtained for vanado-diphosphonate structures. One-dimensional chains in (a) [(VIVO){O3P(CH2)2PO3}]2 , and (b) [(VIVO)2{O3P(CH2)3PO3H}2]2 ; (c) [VIII3{O3P(CH2)2PO3}{HO3P(CH2)2PO3H}3] ; corner-sharing {VIV2O2(OH)} dimers observed in (d) [(VIIIO)VIV2(OH)2{O3P(CH2)2PO3}]2 and (e) [(VIVO)4(OH)2(H2O){O3P(CH2)nPO3}2]2 (n = 3, 5); (f) [(VIVO)2(OH){O3P(CH2)2PO3}] ; (g) edge-sharing {VIV2O8(OH)} dimers in [(VIVO)2(H2O){O3P(CH2)nPO3}] (n = 2–5); (h) [{VVO(H2O)}(VIVO)O{O3P(CH2)2PO3}] ; (i) [VIV2O2(H2O)4{O3P(CH2)6PO3}]; (j) [VIVO{HO3P(CH2)9PO3H}]. Color code {MoOx} bluishgreen polyhedra, {PO3C} magenta tetrahedra.

species [{VVO(H2O)}(VIVO)O{O3P(CH2)2PO3}] {3D-VV(VIVO)PC2P}, built from chains of corner-sharing {VIVO5} squarepyramids alternating with {PO3C} tetrahedra (Fig. 9h).62,66 For the compound [(VIVO)2(H2O)4{O3P(CH2)6PO3}] {3D-(VIVO)2PC6P} alternate lines of {PO3C} tetrahedra and {VIVO6} octahedra are observed, where each {PO3} group of the diphosphonate ligands engages in corner-sharing with three vanadium octahedra, forming a two-dimensional bilayer (Fig. 9i).58 For [VIVO{HO3P(CH2)9PO3H}] (3D-VIVOPC9PH2), alternate vanadyl-phosphonate chains are connected by {PO3C} tetrahedra (Fig. 9j).58 Finally, [VIV3O3{O3P(CH2)2PO3}2]2 {3D-VIV3(PC2P)2} is the only compound that exhibits a three-dimensional V–P–O assembly, This journal is

c


also reported by Zubieta and coworkers.58 The structure of such a compound consists of [VIVO{O3P(CH2)2PO3}]2 n layers linked through {VIVO5} square pyramids. In addition to vanado-diphosphonates with V–P–O assemblies, only four structures with additional fluorine linkages have been reported, possessing interesting lamellar-like connectivity. Zubieta and coworkers have reported a series of such compounds with ethylene-, propylene-, butylene-, and pentylenediphosphonate.67 For [VIII3F2(H2O)2{O3P(CH2)2PO3}2] {3D-VIII3F2(PC2P)2} the layers are made of chains of {VIII2O4F2} dimers, which corner-share via fluorine bridges and are capped by phosphonate groups (Fig. 10a). Such chains are connected by {VIIIO6} octahedra via the phosphonate Chem. Soc. Rev., 2012, 41, 7590–7604

7599

Fig. 10 Figure illustrates the different types of V–P–O/F layers in the fluorine-containing vanado-diphosphonate structure. (a) [VIII3F2(H2O)2{O3P(CH2)2PO3}2] , (b) edge-sharing {VIVVIIIO4F2(H2O)} dimers in [VIV2VIII2F4O2(H2O)2{O3P(CH2)3PO3}2]2 , (c) [VIV2O2F2(H2O)2{O3P(CH2)4PO3}]2 . Color code: {MoOxFx} brown polyhedra, {MoOx} bluish-green polyhedra, {PO3C} magenta tetrahedral; and (d) [VIII6F12(H2O)2{O3P(CH2)5PO3}2{HO3P(CH2)5PO3H}]2 with fluorine equatorial {VIII2F3O4} dimers as brown polyhedra and fluorine axial {VIIIF3O3} units as bluish-green polyhedra. Color code: {MoOx} bluish-green polyhedra, {PO3C} magenta tetrahedra.

groups to form the two-dimensional sheet. The propylenediphosphonate derivative, [VIV2VIII2F4O2(H2O)2{O3P(CH2)3PO3}2]2 {3D-VIV2VIII2F4(PC3P)2}, consists of edge-sharing {VIVVIIIO4F2(H2O)} dimers connected by phosphonate groups to form the two-dimensional sheet (Fig. 10b). The butylenediphosphonate derivative, [VIV2O2F2(H2O)2{O3P(CH2)4PO3}]2 (3D-VIV2F2PC4P), consists of individual {VIVO5F} octahedra connected by phosphonate groups, forming a two-dimensional motif (Fig. 10c) very similar to the one of 3D-(VIVO)2PC6P.58 Lastly, the pentylene-diphosphonate derivative, [VIII6F12(H2O)2{O3P(CH2)5PO3}2{HO3P(CH2)5PO3H}]2 {3D-VIII6F12(PC5P)2(PC5PH2)}, consists of zig–zag chains of {VIII2F3O4} dimers (two fluorines at the equatorial position) connected by {VIIIF3O3} octahedra (two fluorines at the axial position) and phosphonate tetrahedra. These chains are further connected by phosphonate groups to form two-dimensional sheets (Fig. 10d). In both the butylene and pentylene derivatives the phosphonate groups are oriented along one direction, leading to an overall two-dimensional bilayer, similar to compounds previously discussed. 4.1.2 Other types of vanado-diphosphonate structures. Apart from the V–P–O layer-like vanado-diphosphonate structures, 7600

Chem. Soc. Rev., 2012, 41, 7590–7604

several other structures also exist in the literature. This section will try to provide a short overview of all such compounds from one-dimensional chains to three-dimensional frameworks. Detailed study of vanado-diphosphonates reveals that most of such structures are observed to be three-dimensional assemblies, with methylene-diphosphonate as the ligand. The abundantly reported and the only one-dimensional vanado-diphosphonate structure is the zig–zag assembly of [VIVO{O3P–CH2–PO3}]2 (1D-VIVOPCP), formed from IV square-pyramidal {V O5} units connected by diphosphonate ligands.24,56,68 The first two-dimensional structure was reported in 1990 by Jacobson and coworkers.69 Formulated as [(VIVO2)2{O3P–CH2–PO3}] {2D-(VIVO)2PCP}, this compound is constructed of six-membered [VIV3O5{O3P–CH2–PO3}3] rings, connecting with each other to form the two-dimensional architecture. The first three-dimensional vanado-diphosphonate structures were reported by Zubieta and coworkers in 1996, which include the mixed-valent [(VIVO)2VIII(O3P–CH2–PO3)2(H2O)2] {3D-(VIVO)2VIIIPCP2} and mono-valent [VIII(O3P–CH2–PO3H)(H2O)] (3D-VIIIPCPH).24 The structure of 3D-(VIVO)2VIIIPCP consists of a bilayer sheet assembly of [(VIVO){O3P–CH2–PO3}] This journal is

c


units connected by {VIIIO6} octahedra. For 3D-VIIIPCPH however, the structure consists of a complex three-dimensional assembly of {VIIIO6} octahedra and {O3P–CH2–PO3H}3 ligands, resulting in the formation of unusual seven-membered polyhedral rings, each comprising three {VIIIO6} octahedra and four {PO3C} tetrahedra. The synthetic procedure for 3D-VIIIPCPH was later adopted by Fe´rey and coworkers as a route to encapsulate Ag atoms and form the three-dimensional [Ag3(VVO2){O3P–CH2–PO3}] (3D-AgVVO2PCP), where onedimensional chains of corner-linked trimeric vanadiumdiphosphonate units are connected electrostatically by sheets of Ag+ with tetrahedral and square-pyramidal coordination.70 Other three-dimensional structures of vanado-diphosphonates include the [(VIVO)2{VIVO(H2O)}4{O3P–CH2–PO3}4]4 IV IV {3D-(V O)2V PCP4}, isolated as an ammonium salt. The anionic coordination polymer consists of chains of [VIVO{O3P–CH2–PO3}]2 units connected by {VIVO5(H2O)} octahedra along two directions to form the three-dimensional assembly.66 A potassium salt of the compound was also reported later.62 Doubling the amount of solvent during the potassium-salt synthesis of 3D-(VIVO)2VIVPCP4 resulted in the mixed-valent species [(VVO2)4(VIVO){O3P–CH2–PO3}2]2 {3D-(VVO2)4(VIVO)PCP2}.71 The structure of this compound consists of linear chains of edge-sharing {VVO6} octahedra and corner-sharing {VIVO5} square-pyramids, connected extensively by the diphosphonate ligands to form the threedimensional motif. Lastly, several three-dimensional structures of fluorinecontaining vanado-diphosphonates without extensive V–P–O/F connectivities have also been reported in the literature. Examples of such structure types include the compounds [VIV7O6F4(H2O)2{O3P(CH2)2PO3}4]4 {3D-VIV7F4PC2P4} composed of {VIV3O2(H2O)2}8+ trimers connected by diphosphonate ligands to form {VIV6F7O6{O3P(CH2)2PO3}4}n4n layers, which are in turn linked through the central vanadium sites of the trinuclear subunit;67 and [VIV3O3F2(H2O){O3P–CH2–PO3}2]4 (3D-VIV3F2PCP2) consisting of [VIV2O4{O3P–CH2–PO3}]n2n chains linked through {VIVO3(H2O)F2} polyhedra.26 4.2

Molybdo-diphosphonates

In addition to molecular polyoxomolybdates containing diphosphonates, several coordination polymers have also been reported with molybdates, mainly by Vidyasagar and coworkers. The methylene-diphosphonate derivative, formulated as [MoVIO2(O3P–CH2–PO3H)] (2D-MoVIO2PCPH), consists of MoVIO6 octahedra connected by the diphosphonate ligands in sequence to form two-dimensional sheets, with the cations (NH4+, Rb+, and Tl+) occupying the inter-lamellar spaces.72 The three-dimensional compound [(MoVI2O5){O3P(CH2)2PO3}]2 (3D-b-MoVI2PC2P) with ethylene-diphosphonate, consists of two-dimensional anionic layers of dioctahedral {Mo2O11} units connected to four diphosphonate ligands, which are in turn connected to four {Mo2O11} units.73 Such an assembly is also observed for the vanado-diphosphonate 3D-(VIVO)2PC3P.56,61,62 4.3

Rutheno-diphosphonates

The area of diphosphonate-based ruthenium coordination polymers has been mainly covered by Zheng and coworkers. This journal is

c


Fig. 11 Figure illustrates the various connectivities of the monomer (a) [RuII/III2{O3P–C(OH)(CH3)–PO3}2(H2O)2]3 to form (b) linear chains in [RuII2{O3P–C(OH)(CH3)–PO3}2]; (c) two-dimensional sheet in [RuII/III2{O3P–C(OH)(CH3)–PO3}{O3P–C(OH)(CH3)–PO3H}]2 , [RuII/III2{O3P–C(OH)(CH3)–PO3}2][RuII/III2{O3P–C(OH)(CH3)–PO3H}2]4 , [RuII/III2{O3P–C(OH)(CH3)–PO3}]3 ; (d) Kagome arrangement in [RuII/III2{O3P–C(OH)(CH3)–PO3H0.5}2]2 . Color code: Ru bluishgreen, P magenta, O red, C gray, H white.

Chem. Soc. Rev., 2012, 41, 7590–7604

7601

All such polymeric structures consist of the paddle-wheelshaped monomeric unit [RuII/III2{O3P–C(OH)(CH3)–PO3}2]3 (Fig. 11). The difference in connectivity of this unit leads to the formation of monomeric and polymeric structures. The discrete II/III monomeric unit [Ru 2{O3P–C(OH)(CH3)–PO3}2(H2O)2]3 has an outward terminal aqua ligand.74b The one-dimensional chain can be simple [RuII2{O3P–C(OH)(CH3)–PO3}2]N,74d halidebridged [RuII/III2{O3P–C(OH)(CH3)–PO3}2X]N (X = Cl, Br), or cyanoferrate-bridged [RuII/III2{O3P–C(OH)(CH3)–PO3}2{FeII(CN)6}]N7 .74b Formation of two-dimensional sheets are observed for [RuII/III2{O3P–C(OH)(CH3)–PO3}{O3P–C(OH)(CH3)–PO3H}]2 , [RuII/III2{O3P–C(OH)(CH3)–PO3}2][RuII/III2{O3P–C(OH)(CH3)–PO3H}2]4 , and [RuII/III2{O3P–C(OH)(CH3)–PO3}2]3 .74a,d,e Finally, the extended [RuII/III2{O3P–C(OH)(CH3)–PO3H0.5}2]N2 has a kagome-type structure.74c 4.4

Actinide-diphosphonates

Coordination polymers of metal-diphosphonates have also been reported with several actinides. Due to the metals having high coordination numbers with many bonding possibilities, this results in overall complex structure types. The first of such compounds were reported in 2008 by Albrecht-Schmitt and coworkers, with discrete metal-oxo units connected by diphosphonate ligands.75 The three-dimensional (UVIO2)2(O3PCH2PO3)(H2O)3H2O consists of corrugated layers containing {UVIO6} squarebipyramidal and {UVIO7} pentagonal-bipyramidal units bridged by diphosphonate ligands. For the compound UVIO2(O3PCH2PO3H)2(H2O) a polar three-dimensional network of exclusive pentagonal bipyramidal {UVIO7} units was observed. Isoreticular NpIV(O3PCH2PO3)(H2O)2 and UIV(O3PCH2PO3)2(H2O) adopt three-dimensional structures with eight-coordinate and seven-coordinate metal centers, respectively. The An(IV) (An = U, Np) centers are then coordinated by methylenediphosphonate and water molecules to form the framework. The analogous Th(IV) and Pu(IV) derivatives, ThIV(O3PCH2PO3)(H2O)2 and PuIV(O3PCH2PO3)(H2O), were also reported by the same group.76 Several isomers of the Pu(IV)-derivative, classified as a-, b-, and g-PuIV(O3PCH2PO3)(H2O), depending upon the coordination geometry of Pu(IV), were also structurally characterized.77 Several reports exist of urano-diphosphonate coordination polymers with interesting structural features. The heterobimetallic U(VI)/An(IV) diphosphonate, UVIO2AnIV(H2O)2(O3PCH2PO3H)]2 (An = Th, Np, Pu), forms a three-dimensional network of {UVIO6} tetragonal bipyramids and {AnIVO8} distorted dodecahedra.76 The chiral porous frameworks of [UVIO2(O3PCH2PO3)]4 and [(UVIO2)3(O3PCH2PO3)2]2 consist VI of {U O7} pentagonal bipyramidal units with methylenediphosphonate ligands bridging between the units.78 Presence of discrete {UVIO7} units are observed for [UVIO2(O3PCH2PO3)]4 , while for [(UVIO2)3(O3PCH2PO3)2]2 the metal atoms are either discrete or form edge-sharing dimers. In the mixed-valent urano(IV,VI)diphosphonate, [(UVIO2)3UIV(H2O)2(O3PCH2PO3)3]2 , tetravalent uranium centers adopt eight coordinate squareanti-prism geometries, while hexavalent uranyl units have seven coordinate tetragonal bipyramidal geometry.79 Finally Cahill and coworkers have reported in 2010 a series of urano-diphosphonate with varying dimensionalities.80 The one-dimensional chains of 7602

Chem. Soc. Rev., 2012, 41, 7590–7604

(UVIO2)(O3PCH2PO3H)(H2O) consist of pentagonal bipyramids constructed from UO22+ cations equatorially bound to five oxygen atoms from three acid units and a bound water molecule connected linearly by methylene-diphosphonate groups. For (UVIO2)(O3PCH2PO3H)(H2O) , monomers of U(VI) pentagonal bipyramids are linked via methylene-diphosphonate units to form the two-dimensional sheets. The three-dimensional structure of (UVIO2)(O3PCH2PO3H)(H2O) consists of chains of U(VI) monomers linked via diphosphonate units, further connected along [010] and [001] by the diphosphonate ligands.

5. Conclusions and outlook This review has compiled all published results on diphosphateand diphosphonate-containing POMs with an emphasis on synthetic and structural aspects. In this endeavor we initially discussed the diphosphate anion and its chemistry and emphasized its reactivity towards different POM systems. Subsequently, we discussed the reasons for the introduction of diphosphonate into POMs, highlighting the robustness of such a ligand and its versatility for functionality allowing for tailor-made properties in the final POM. Furthermore, the discussion on diphosphonate has yielded insight into the behavior and properties of diphosphonate-POM compounds. Several of the compounds obtained have already shown an interesting array of properties ranging from therapeutic action to optical activity and homogeneous catalysis, among others. It can be concluded with confidence that the combined and dedicated efforts of so many research groups over a rather short period of time has revealed a vast and beautiful array of compounds, which may in fact just be the tip of the iceberg. Many more interesting species and functionalities remain to be explored and examined, predicting that this area of POM chemistry will continue to flourish.

6. List of abbreviations for ligands and structural units POP PCP PCPH PCPH2 PCnP PCnPH PCnPH2 PEP Etid HEtid HEtidH F3-Etid Alen MeAlen Me2Alen PhAlen Risd 4-PyrPC2OP PAHC5P PCNMe2P Acet

(O3P–O–PO3) (O3P–CH2–PO3) (O3P–CH2–PO3H) (HO3P–CH2–PO3H) {O3P–(CH2)n–PO3} (n > 1) {O3P–(CH2)n–PO3H} (n > 1) {HO3P–(CH2)n–PO3H} (n > 1) {H2CQC(PO3)2} {O3P–C(O)(CH3)–PO3} {O3P–C(OH)(CH3)–PO3} {O3P–C(OH)(CH3)–PO3H} {O3P–C(O)(CF3)–PO3} {O3P–C(O)(C3H6NH3)–PO3} {O3P–C(O)(C3H6N(CH3)H2)–PO3} {O3P–C(O)(C3H6N(CH3)2H)–PO3} {O3P–C(O)(C10H14NO)–PO3} {O3P–C(O)(CH2-3-C5NH4)–PO3} {O3P–C(O)(CH2-4-C5NH4)–PO3} {O3P–C(O)(C4H8NH3)–PO3} {O3P–CH(NMe2)–PO3} (CH3COO)

This journal is

c


Form Met MeAs a-MoVI2 b-MoVI2 MoV2

(HCOO) (OCH3) (CH3AsO3) (MoVI2O6) (MoVI2O5) (MoV2O4)

19

20 21

References

22

1 (a) M. T. Pope, Heteropoly and Isopoly Oxometalates, SpringerVerlag, Berlin, 1983; (b) M. T. Pope and A. Mu¨ller, Angew. Chem., Int. Ed. Engl., 1991, 30, 34–38; (c) C. L. Hill and C. M. ProsserMcCartha, Coord. Chem. Rev., 1995, 143, 407–455; (d) Special Issue on Polyoxometalates, ed. C. L. Hill, Chem. Rev., 1998, 98; (e) A. Mu¨ller and S. Roy, Coord. Chem. Rev., 2003, 245, 153–166; (f) L. Cronin, Comprehensive Coordination Chemistry II, vol. 7, ed. J. A. McCleverty and T. J. Meyer, Elsevier, Amsterdam, 2004; (g) B. Hasenknopf, K. Micoine, E. Lacoˆte, S. Thorimbert, M. Malacria and R. Thouvenot, Eur. J. Inorg. Chem., 2008, 5001–5013; (h) U. Kortz, A. Mu¨ller, J. van Slageren, J. Schnack, N. S. Dalal and M. Dressel, Coord. Chem. Rev., 2009, 253, 2315–2327; (i) U. Kortz. Guest Ed. Issue dedicated to Polyoxometalates. Eur. J. Inorg. Chem., 2009, 5055-5276; (j) D. L. Long, R. Tsunashima and L. Cronin, Angew. Chem., Int. Ed., 2010, 49, 1736–1758. 2 (a) H. Fleisch, Bisphosphonates in Bone Diseases From the Laboratory to the Patient, Academic Press, San Diego, California, USA, 2000; (b) M. D. Francis and D. J. Valent, J. Musculoskeletal. Neuronal. Interact., 2007, 7, 2–8; (c) R. Bartl, B. Frisch, E. Tresckow and C. Bartl, Bisphosphonatesin Medical Practice, Springer-Verlag, Berlin, Heidelberg, 2007; (d) D. Heymann (Guest ed.), Special issue on bisphosphonates, Curr. Pharm. Des., 2010, 16, 2948–3052. 3 J. T. Rhule, C. L. Hill and D. A. Judd, Chem. Rev., 1998, 98, 327–357. 4 (a) X. H. Wang, J. F. Liu, Y. G. Chen, Q. Liu, J. T. Liu and M. T. Pope, J. Chem. Soc., Dalton Trans., 2000, 1139–1141; (b) B. Hasenknopf, Front. Biosci., 2005, 10, 275–287; (c) M. Aureliano and D. C. Crans, J. Inorg. Biochem, 2009, 103, 536–546; (d) Z. Dong, R. Tan, J. Cao, Y. Yang, C. Kong, J. Du, S. Zhu, Y. Zhang, J. Lu, B. Huang and S. Liu, Eur. J. Med. Chem., 2011, 46, 2477–2484. 5 H. Fleisch, Breast Cancer Res., 2002, 4, 30–34. 6 J. C. Frith, J. Mo¨nkko¨nen, G. M. Blackburn, R. G. G. Russel and M. J. Rogers, J. Bone Miner. Res., 1997, 12, 1358–1367. 7 E. V. Beek, C. Lo¨wik, G. V. D. Pluijm and S. Papapoulos, J. Bone Miner. Res., 1999, 14, 722–729. 8 (a) O. W. Gibbs, Proc. Am. Acad. Arts Sci., 1886, 21, 107–114; (b) A. Rosenheim and M. Schapiro, Z. Anorg. Chem., 1923, 129, 196–205. 9 U. Kortz, G. B. Jameson and M. T. Pope, J. Am. Chem. Soc., 1994, 116, 2659–2660. 10 S. G. Sarafianos, U. Kortz, M. T. Pope and M. J. Modak, Biochem. J., 1996, 319, 619–626. 11 S. Himeno, T. Katsuta, M. Takamoto and M. Hashimoto, Bull. Chem. Soc. Jpn., 2006, 79, 100–105. 12 (a) U. Kortz and M. T. Pope, Inorg. Chem., 1994, 33, 5643–5646; (b) S. Himeno, A. Saito and T. Hori, Bull. Chem. Soc. Jpn., 1990, 63, 1602–1606. 13 S. Himeno, T. Kubo, A. Saito and T. Hori, Inorg. Chim. Acta, 1995, 236, 167–171. 14 S. Himeno, T. Ueda, M. Shiomi and T. Hori, Inorg. Chim. Acta, 1997, 262, 219–223. 15 U. Kortz, Inorg. Chem., 2000, 39, 623–624. 16 (a) S. Maeda, T. Goto, M. Takamoto, K. Eda, S. Himeno, H. Takahashi and T. Hori, Inorg. Chem., 2008, 47, 11197–11201; (b) K. Eda, S. Maeda, S. Himeno and T. Hori, Polyhedron, 2009, 28, 4032–4038. 17 U. Kortz, Inorg. Chem., 2000, 39, 625–626. 18 (a) J. Ling, J. Qiu, G. E. Sigmon, M. Ward, J. E. S. Szymanowski and P. C. Burns, J. Am. Chem. Soc., 2010, 132, 13395–13402; (b) J. Ling, J. Qiu, J. E. S. Szymanowski and P. C. Burns, Chem.–Eur. J., 2011, 17, 2571–2574; (c) D. K. Unruh, J. Ling,

This journal is

c


23 24 25 26 27 28 29 30

31 32 33 34 35

36

37 38 39 40 41 42 43

44 45

J. Qiu, L. Pressprich, M. Baranay, M. Ward and P. C. Burns, Inorg. Chem., 2011, 50, 5509–5516. (a) N. Herron, D. L. Thorn, R. L. Harlow and G. W. Coulston, J. Am. Chem. Soc., 1997, 119, 7149–7150; (b) D. Solis-Ibarra, J. S. Silvia, V. Jancik and C. C. Cummins, Inorg. Chem., 2011, 50, 9980–9984. C. du Peloux, P. Mialane, A. Dolbecq, J. Marrot and F. Sećheresse, Angew. Chem., Int. Ed., 2002, 41, 2808–2810. Q. Li and S. W. Zhang, Z. Anorg. Allg. Chem., 2005, 631, 2490–2496. J. Peng, W. Li, E. Wang and Q. Bai, J. Chem. Soc., Dalton Trans., 2001, 3668–3671. H. Fleisch, Clin. Orthop. Relat. Res., 1987, 72–78. G. Bonavia, R. C. Haushalter, C. J. O’Connor and J. Zubieta, Inorg. Chem., 1996, 35, 5603–5612. J. Salta and J. Zubieta, lnorg. Chim. Acta, 1996, 252, 431–434. T. M. Smith, M. Tichenor, J. M. Vargas, C. J. O’Connor and J. Zubieta, Inorg. Chim. Acta, 2011, 378, 250–256. G. G. Aleksandrov, V. S. Sergienko and E. G. Afonin, Crystallogr. Rep., 2001, 46, 46–50. U. Kortz and M. T. Pope, Inorg. Chem., 1995, 34, 2160–2163. C. du Peloux, P. Mialane, A. Dolbecq, J. Marrot and F. Sećheresse, Dalton Trans., 2004, 1259–1263. A. Banerjee, B. S. Bassil, G.-V. Ro¨schenthaler, U. Kortz, unpublished results. Crystal data for Na26[Na2(H2O)5{(MoV2O4)10{H2CQC(PO3)2}10(CH3COO)8 (H2O)4}]79H2O, Monoclinic C2/m, a = 20.4308(2) A˚, b = 36.2131(3) A˚, c = 17.5389(2) A˚, b = 116.451, V = 11617.85(17) A˚3. Crystal data for Na21[Na9(H2O)35{(MoV2O4)10{H2CQC(PO3)2}10(HCOO)10}]45H2O, Monoclinic C2/c, a = 35.6421(1) A˚, b = 20.8301(6) A˚, c = 35.5475(1) A˚, b = 98.04(0)1, V = 26131.81(75) A˚3. E. Dumas, C. Sassoye, K. D. Smith and S. C. Sevov, Inorg. Chem., 2002, 41, 4029–4032. A. Dolbecq, L. Lisnard, P. Mialane, J. Marrot, M. Beńard, M. M. Rohmer and F. Sećheresse, Inorg. Chem., 2006, 45, 5898–5910. A. Dolbecq, J. D. Compain, P. Mialane, J. Marrot, F. Sećheresse, B. Keita, L. R. B. Holzle, F. Miserque and L. Nadjo, Chem.–Eur. J., 2009, 15, 733–741. E. V. Beek, M. Hoekstra, M. V. D. Ruit, C. Lowik and S. Papapoulos, J. Bone Miner. Res., 1994, 9, 1875–1882. (a) I. A. Krol, Z. A. Starikova, V. S. Sergienko and E. O. Tolkacheva, Mendeleev Commun., 1991, 1, 7–8; (b) V. S. Sergienko, E. O. Tolkacheva, A. B. Ilyukhin, Z. A. Starikova and I. A. Krol, Mendeleev Commun., 1992, 4, 144–146; (c) I. A. Krol, Z. A. Starikova, E. O. Tolkacheva, V. S. Sergienko and S. S. Makarevich, Zh. Neorg. Khim., 1992, 37, 304–314; (d) V. S. Sergienko, E. O. Tolkacheva, A. B. Ilyukhin and Z. A. Starikova, Zh. Neorg. Khim., 1993, 38, 1311–1316; (e) V. S. Sergienko, Kristallografiya, 1999, 44, 939–955. (a) I. A. Krol, Z. A. Starikova, V. S. Sergienko and E. O. Tolkacheva, Zh. Neorg. Khim., 1990, 35, 2817–2827; (b) E. O. Tolkacheva, I. A. Krol, Z. A. Starikova, V. S. Sergienko, V. S. Popov and M. Z. Gurevich, Zh. Neorg. Khim., 1992, 37, 315–327. J. D. Compain, A. Dolbecq, J. Marrot, P. Mialane and F. Sećheresse, C. R. Chim., 2010, 13, 329–335. J. D. Compain, P. Mialane, J. Marrot, F. Sećheresse, W. Zhu, E. Oldfield and A. Dolbecq, Chem.–Eur. J., 2010, 16, 13741–13748. A. Banerjee, N. V. Izarova, G.-V. Ro¨schenthaler,U. Kortz, manuscript in preparation. H. Q. Tan, W. L. Chen, D. Liu and E. B. Wang, J. Cluster. Sci., 2010, 21, 147–154. H. Q. Tan, W. L. Chen, D. Liu, Y. G. Li and E. B. Wang, CrystEngComm, 2010, 12, 4017–4019. A. Banerjee, F. S. Raad, N. Vankova, B. S. Bassil, T. Heine and U. Kortz, Inorg. Chem., 2011, 50, 11667–11675. (a) G.-V. Ro¨schenthaler, Nachr. Chem., 2005, 53, 743–746; (b) P. Kirsch, Modern Fluoroorganic Chemistry, Wiley-VCH Verlag, Weinheim, 2004; (c) K. Uneyama, Organofluorine Chemistry, Blackwell Publishing, UK, 2006; (d) I. Ojima, Fluorine in Medicinal Chemistry and Chemical Biology, Wiley-Blackwell, UK, 2009. A. Banerjee, B. S. Bassil, G.-V. Ro¨schenthaler and U. Kortz, Eur. J. Inorg. Chem., 2010, 3915–3919. H. Tan, W. Chen, D. Liu, X. Feng, Y. Li, A. Yan and E. Wang, Dalton Trans., 2011, 8414–8418.

Chem. Soc. Rev., 2012, 41, 7590–7604

7603

46 H. E. Moll, A. Dolbecq, I. M. Mbomekalle, J. Marrot, P. Deniard, R. Dessapt and P. Mialane, Inorg. Chem., 2012, 51, 2291–2302. 47 J.-D. Compain, P. Deniard, R. Dessapt, A. Dolbecq, O. Oms, F. Sećheresse, J. Marrot and P. Mialane, Chem. Commun., 2010, 7733–7735. 48 L. Zhang, J. Sun, Y. Zhou, S. u. Hassan, E. Wang and Z. Shi, CrystEngComm, 2012, 14, 4826–4833. 49 J. Niu, X. Zhang, D. Yang, J. Zhao, P. Ma, U. Kortz and J. Wang, Chem.–Eur. J., 2012, 18, 6759–6762. 50 H. Tan, W. Chen, D. Liu, Y. Li and E. Wang, Dalton Trans., 2010, 39, 1245–1249. 51 U. Kortz and M. T. Pope, Inorg. Chem., 1995, 34, 3848–3850. 52 (a) V. S. Sergienko, E. A. Tolkacheva and A. B. Ilyukhin, Zh. Neorg. Khim., 1994, 39, 243–251; (b) V. S. Sergienko, E. O. Tolkacheva and A. B. Ilyukhin, Koord. Khim., 1994, 20, 195–207; (c) V. S. Sergienko, E. O. Tolkacheva and A. B. Ilyukhin, Kristallografiya, 1994, 39, 1020–1024. 53 E. O. Tolkacheva, V. S. Sergienko, A. B. Ilyukhin and S. V. Mehskov, Zh. Neorg. Khim., 1997, 42, 752–764. 54 H. E. Moll, A. Dolbecq, J. Marrot, G. Rousseau, M. Haouas, F. Taulelle, G. Rogez, W. Wernsdorfer, B. Keita and P. Mialane, Chem.–Eur. J., 2012, 18, 3845–3849. 55 (a) R. M. Barrer, Hydrothermal Chemistry of Zeolites, Academic Press, London, 1982; (b) S. T. Wilson, B. M. Lok, C. A. Mesina, T. R. Cannan and E. D. Flanigen, J. Am. Chem. Soc., 1982, 104, 1146–1147; (c) J. Yu and R. Xu, Chem. Soc. Rev., 2006, 35, 593–604, and references therein. 56 V. Soghomonian, Q. Chen, R. C. Haushalter and J. Zubieta, Angew. Chem. Int. Ed., 1995, 34, 223–226. 57 V. Soghomonian, R. Diaz, R. C. Haushalter, C. J. O’Connor and J. Zubieta, Inorg. Chem., 1995, 34, 4460–4466. 58 W. Ouellette, M. H. Yu, C. J. O’Connor and J. Zubieta, Inorg. Chem., 2006, 45, 3224–3239. 59 V. Soghomonian, R. C. Haushalter and J. Zubieta, Chem. Mater., 1995, 7, 1648–1654. 60 Y. Hayashi, Coord. Chem. Rev., 2011, 255, 2270–2280. 61 D. Riou and G. Fe´rey, J. Mater. Chem., 1998, 8, 2733–2735. 62 D. Riou, P. Baltazar and G. Fe´rey, Solid State Sci., 2000, 2, 127–134.

7604

Chem. Soc. Rev., 2012, 41, 7590–7604

63 G. H. Bonavia, R. C. Haushalter, S. Lu, C. J. O’Conner and J. Zubieta, J. Solid State Chem., 1997, 132, 144–150. 64 D. Riou, C. Serre and G. Fe´rey, J. Solid State Chem., 1998, 14111, 89–93. 65 D. Riou, C. Serre, J. Provost and G. Fe´rey, J. Solid State Chem., 2000, 155, 238–242. 66 D. Riou, O. Roubeau and G. Fe´rey, Microporous Mesoporous Mater., 1998, 23, 23–31. 67 W. Ouellette, M. H. Yu, C. J. O’Connor and J. Zubieta, Inorg. Chem., 2006, 45, 7628–7641. 68 C. Ninclaus, C. Serre, D. Riou and G. Fe´rey, C. R. Acad. Sci., Paris Ser. IIc : Chim., 1998, 551–556. 69 G. Huan, J. W. Johnson and A. J. Jacobson, J. Solid State Chem., 1990, 89, 220–225. 70 K. Barthelet, D. Riou and G. Fe´rey, Solid State Sci., 2001, 3, 203–209. 71 D. Riou, C. Serre and G. Fe´rey, Int. J. Inorg. Mater., 2000, 2, 551–556. 72 M. P. Minimol, K. P. Rao, Y. R. Sai and K. Vidyasagar, Proc. Indian Acad. Sci., 2003, 115, 419–429. 73 K. P. Rao, V. Balraj, M. P. Minimol and K. Vidyasagar, Inorg. Chem., 2004, 43, 4610–4614. 74 (a) X.-Y. Yi, L.-M. Zheng, W. Xu and S. Feng, Inorg. Chem., 2003, 42, 2827–2829; (b) X.-Y. Yi, B. Liu, R. Jimeńez-Aparicio, F. A. Urbanos, S. Gao, W. Xu, J.-S. Chen, Y. Song and L.-M. Zheng, Inorg. Chem., 2005, 44, 4309–4314; (c) B. Liu, Y.-Z. Li and L.-M. Zheng, Inorg. Chem., 2005, 44, 6921–6923; (d) B. Liu, P. Yin, X.-Y. Yi, S. Gao and L.-M. Zheng, Inorg. Chem., 2006, 45, 4205–4213; (e) B. Liu, Y.-Z. Li and L.-M. Zheng, Solid State Sci., 2006, 8, 1041–1045. 75 A.-G. D. Nelson, T. H. Bray, W. Zhan, R. G. Haire, T. S. Sayler and T. E. Albrecht-Schmitt, Inorg. Chem., 2008, 47, 4945–4951. 76 A.-G. D. Nelson, T. H. Bray, F. A. Stanley and T. E. AlbrechtSchmitt, Inorg. Chem., 2009, 48, 4530–4535. 77 J. Diwu, A.-G. D. Nelson, S. Wang, C. F. Campana and T. E. Albrecht-Schmit, Inorg. Chem., 2010, 49, 3337–3342. 78 J. Diwu and T. E. Albrecht-Schmit, Chem. Commun., 2012, 3827–3829. 79 J. Diwu and T. E. Albrecht-Schmit, Inorg. Chem., 2012, 51, 4432–4434. 80 K. E. Knope and C. L. Cahill, Dalton Trans., 2010, 8319–8324.

This journal is

c
