Journal of Structural Chemistry. Vol. 47, No. 1, pp. 97-101, 2006 Original Russian Text Copyright © 2006 by S. S. Yarovoi, S. F. Solodovnikov, Z. A. Solodovnikova, Yu. V. Mironov, and V. E. Fedorov
SYNTHESIS AND CRYSTAL STRUCTURE OF THE OCTAHEDRAL CLUSTER COMPLEX [Th(DMSO)8Cl][Re6Se7Cl7] S. S. Yarovoi, S. F. Solodovnikov, Z. A. Solodovnikova, Yu. V. Mironov, and V. E. Fedorov
UDC 548.736
A cluster complex of the composition [Th(DMSO)8Cl][Re6Se7Cl7] has been obtained by interaction of ThCl4 solution in DMSO with a water solution of K3[Re6Se7Cl7] and KCl. The compound crystallizes in the rhombic space group Pbcm with unit cell parameters a = 12.262(2) Å, b = 19.653(6) Å, c = 23.603(6) Å, V = 5688(2) Å3, Z = 4, dcalc = 3.282 g/cm3. The structure is built from centrosymmetric cluster anions [Re6Se7Cl7]3 and complex cations [Th(DMSO)8Cl]3+ possessing mirror-plane symmetry, half of the DMSO ligands being doubly disordered. Keywords: rhenium, thorium, octahedral selenium bromide cluster, synthesis, crystal structure, structural disorder.
The formation of chalcohalide metal cluster complexes is one of the most specific features of the coordination chemistry of rhenium. These clusters are known both in the form of polymers and island-type anionic complexes [1-5]. As a rule, the ionic compounds incorporate as counterions large alkali metal cations or organic cations, like tetraalkylammonium, tetraphosphonium and others. In the course of this study we have prepared and structurally characterized a novel ionic complex [Th(DMSO)8Cl][Re6Se7Cl7] comprising the cluster anion [Re6Se7Cl7]3– and the complex cation [Th(DMSO)8Cl]3+. Synthesis of [Th(DMSO)8Cl][Re6Se7Cl7]. Cluster salt of K3[Re6Se7Cl7] stoichiometry was prepared by a hightemperature reaction (evacuated quartz ampoule, 850qɋ, 72 h) from a mixture of K2ReCl6, Re, Se and an excess of KCl. Reaction products were dissolved in acetonitrile.* The resulted solution was added with a saturated solution of ThCl4 in DMSO, few drops of hydrochloric acid being added to enhance solubility. In two days the solution yielded dark-red crystals suitable for an X-ray diffraction structural study. X-ray diffraction experiment. Intensity data for the structure determination were collected at room temperature from a fragment of a platelet crystal (0.32u0.32u0.20 mm) mounted on an automated diffractometer Enraf-Nonius CAD-4 (MoKD-radiation, graphite monochromator, Z/2T-scanning, 2Tmax = 55q). A total of 5083 reflections was measured including 5066 independent ones (Rint = 0.1402). Crystal system is rhombic, space group is Pbcm, a = 12.262(2) Å, b = 19.653(6) Å, c = 23.603(6) Å, Vcell = 5688(2) Å3, Z = 4, dcalc = 3.282 g/cm3. Extinction correction (P = 20.501 mm–1) was applied using azimuthal scans. The structure was solved by the direct method and refined anisotropically for heavy atoms using the
*A 77Se NMR study of this solution revealed that, along with the dominating form [Re6Se7Cl7]3–, the solution contains octahedral anionic complexes having a different composition. The formation of a series of anionic complexes [{Re6Q8–xClx]Cl6}(4–x)– under these conditions is explained by the equilibrium between the forms of different composition occurring at high temperature in the KCl melt. Nikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences, Novosibirsk;
[email protected]. Translated from Zhurnal Strukturnoi Khimii, Vol. 47, No. 1, pp. 100-103, January-February, 2006. Original article submitted April 20, 2005. 0022-4766/06/4701-0097 © 2006 Springer Science+Business Media, Inc.
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TABLE 1. Atomic Coordinates, Occupation Factors and Equivalent Isotropic Thermal Parameters (Å2) of Independent Atoms for [Th(DMSO)8Cl][Re6Se7Cl7] Atom
Occupation factor
x/a
y/b
z/c
U(eq)*, Å2
Th Re(1) Re(2) Re(3) Se(1) Cl(1A) Se(2) Cl(2A) Se(3) Cl(3A) Se(4) Cl(4A) Cl(1) Cl(2) Cl(3) Cl(4) O(1) S(1) C(11) C(12) O(2) S(21) S(22) C(21) C(22) O(3) S(3) C(31) C(32) O(4) S(4) C(41) C(42) O(5) S(5) C(51) C(52)
1 1 1 1 0.955(3) 0.045 0.800(6) 0.200 0.962(6) 0.038 0.782(6) 0.218 1 1 1 1 1 1 1 1 1 0.62(2) 0.38 1 1 1 0.5 1 1 1 0.5 1 1 1 1 1 1
0.03077(10) 0.47386(7) 0.63453(7) 0.43788(7) 0.2854(2) 0.2854 0.5417(2) 0.5417 0.4048(2) 0.4048 0.6640(2) 0.6640 0.4485(6) 0.8112(5) 0.3587(6) 0.0262(11) –0.0388(15) –0.1234(7) –0.197(2) –0.057(2) 0.175(2) 0.2083(10) 0.2707(17) 0.341(3) 0.239(2) –0.166(3) –0.2648(10) –0.353(3) 0.333(4) 0.166(3) 0.7633(15) 0.783(4) 0.616(5) –0.014(2) –0.0650(12) –0.113(3) 0.014(2)
–0.30268(6) 0.06878(5) 0.03760(5) 0.05181(4) 0.0796(1) 0.0796 0.1520(1) 0.1520 –0.0190(1) –0.0190 0.0510(2) 0.0510 0.1604(3) 0.0905(3) 0.1183(4) –0.1599(5) –0.2653(9) –0.2184(4) –0.256(1) –0.155(1) –0.273(1) –0.2228(6) –0.2754(12) –0.197(2) –0.274(1) –0.308(2) –0.3156(9) –0.252(2) 0.102(3) –0.3915(18) 0.0668(11) –0.033(3) 0.051(3) –0.397(1) –0.4299(6) –0.511(2) –0.444(1)
0.25 0.44844(4) 0.51596(4) 0.55672(4) 0.4891(1) 0.4891 0.5205(1) 0.5205 0.3810(1) 0.3810 0.4113(1) 0.4113 0.3821(3) 0.5345(3) 0.6327(3) 0.25 0.3458(8) 0.3613(4) 0.417(1) 0.399(1) 0.185(1) 0.3530(5) 0.1546(8) 0.164(1) 0.87(1) 0.25 0.2771(6) 0.25 0.25 0.25 0.2743(6) 0.25 0.25 0.188(1) 0.1444(5) 0.164(2) 0.085(1)
0.0393(3) 0.0339(2) 0.0342(2) 0.0347(2) 0.044(1) 0.044 0.046(1) 0.046 0.045(1) 0.045 0.045(1) 0.045 0.064(2) 0.054(2) 0.068(2) 0.090(4) 0.076(6) 0.083(3) 0.062(8) 0.087(10) 0.101(8) 0.057(4) 0.065(8) 0.10(1) 0.08(1) 0.11(1) 0.071(5) 0.07(1) 0.13(2) 0.12(1) 0.105(7) 0.11(2) 0.13(2) 0.101(7) 0.163(6) 0.12(1) 0.08(1)
*U(eq) = (U11 + U22 + U33)/3. full-matrix least squares technique (oxygen and carbon atoms of DMSO molecules were refined isotropically, hydrogen atoms were not located) with SHELX-97 program package [6]. To match the charge of the complex cation, the composition of the cluster anion was set as [Re6Se7Cl7]3–, or [Re6{P3-(Se, Cl)8}Cl6]3–; Se/Cl ratio in the P3-Q positions (Q = Se1xClx ) was refined to conform this stoichiometry. Final agreement factors were: R(F) = 0.0463, wR(F 2) = 0.1016 for 2504 Fhkl t 4V(F); R(F) = 0.1164, wR(F 2) = 0.1170 for all 5066 unique reflections. Positional and equivalent thermal parameters for the independent atoms in the structure of [Th(DMSO)8Cl][Re6Se7Cl7] are listed in Table 1, selected bond lengths — in Table 2. Discussion. According to the X-ray structural data, the unit cell of [Th(DMSO)8Cl][Re6Se7Cl7] contains four crystallographically equivalent cluster anions [Re6Se7Cl7]3–. The structure of the anion is typical for rhenium(III) octahedral clusters. Six rhenium atoms make a Re6 octahedron inscribed in the cube of eight P3-Se/Cl ligands. In addition, each of the rhenium atoms is coordinated with a chlorine ion (terminal ligand). Re–Re distances in the cluster anion vary within
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TABLE 2. Selected Bond Lengths d, Å for [Th(DMSO)8Cl][Re6Se7Cl7] Bond
d
Bond
d
Bond
d
Th–O(4) Th–O(3) Th–O(5) Th–O(5)#1 Th–O(2) Th–O(2)#1
2.40(4) 2.41(3) 2.42(2) 2.42(2) 2.42(2) 2.42(2)
Re(1)–Re(2)#2 Re(1)–Re(3)#2 Re(1)–Re(3) Re(2)–Re(3) Re(2)–Re(3)#2
2.616(1) 2.608(1) 2.615(1) 2.611(1) 2.611(1)
2.53(2) 2.53(2) 2.81(1) 2.607(1)
2.494(3) 2.502(3) 2.511(3) 2.516(3) 2.506(3)
2.507(3) 2.510(3) 2.521(3) 2.493(3) 2.496(3) 2.509(3)
Th–O(1)#1 Th–O(1) Th–Cl(4) Re(1)–Re(2)
Re(1)–Q(3) Re(1)–Q(2) Re(1)–Q(1) Re(1)–Q(4) Re(2)–Q(3)#2
Re(2)–Q(1)#2 Re(2)–Q(4) Re(2)–Q(2) Re(3)–Q(4)#2 Re(3)–Q(2) Re(3)–Q(3)#2 Re(3)–Q(1) Re(1)–Cl(1) Re(2)–Cl(2) Re(3)–Cl(3)
2.518(3) 2.406(6) 2.442(6) 2.422(6)
Note. Operations generating symmetry-related atoms: #1 x, y, –z + 1/2; #2 –x + 1, –y, –z + 1.
Fig. 1. General view of the complex cation [Th(DMSO)8Cl]3+, DMSO ligands are partially disordered. 2.607(1)-2.616(1) Å (average value 2.611 Å); Re-(P3-Q) — 2.493(3)-2.521(3) Å (average value 2.507 Å); Re–Cl 2.406(6)2.442(6) Å (average value 2.423 Å). The complex cation [Th(DMSO)8Cl]3+ includes a Th4+ ion coordinated with eight DMSO molecules and a chloride ion (CN 9) (Fig. 1). The DMSO molecules are bound to Th4+ through oxygen atoms. Th4+—O distances range from 2.40(3) Å to 2.51(2) Å, and the Th4+–Cl bond length is 2.81(1) Å. The cation lays on the mirror plane which also incorporates two DMSO molecule and the chorine atom, while the other three coordinated dimethylsulfoxide ligands occupy general positions. Three of the five symmetry-independent DMSO molecules are disordered and each has two alternative orientations discriminated by the positions of sulfur atoms. The geometry of DMSO molecules does not go beyond the usual one, although the disordered molecules are characterized by a significantly larger dispersion of bond lengths: for the completely ordered molecules S–O is 1.37(2)1.44(2) Å, S–C 1.73(3)-1.76(3) Å, and for the disordered ones S–O is 1.30(2)-1.39(2) Å, S–C 1.65(4)-2.05(5) Å. An observable deviation of the latter bond lengths from the normal values can be related to an additional (but neglected by us) “splitting” of the methyl carbon positions in the disordered DMSO molecules. The complex cations and anions follow the structural motif of CsCl yielding nearly square alternating cationic and anionic layers (Fig. 2) joined by electrostatic and van der Waals forces. 99
Fig. 2. Crystal structure of [Th(DMSO)7Cl][Re6Se7Cl7] projected onto the (100) plane.
The formation of compounds combining bulky isolated complex anions and cations, including cluster chalcogenide anions and DMSO-coordinated large cations Ca2+ and Ln3+, is not exceptional. The most similar examples comprise [Ln(DMSO)8][Cr(SCN)6] [7, 8], [Ca(DMSO)6][Re6S6Br8] [9] and [Ln(DMSO)n(H2O)m][Mo3S7Br7] [10, 11]. In these compounds the cations and anions are in the simplest stoichiometric ratio 1:1 making it possible, apparently, to crystallize in motifs similar to highly symmetric atomic arrangements of binary compounds Ⱥɏ. It is this fact that appears to account for an interesting peculiarity of the complex under consideration containing cations [Th(DMSO)8Cl]3+, where the coordination environment of the thorium cation involves, alongside with DMSO molecules, one chlorine anion. The formation of such cation balances the charges of the complex cation and the anion permitting the achievement of the desired 1:1 ratio. Coordination number 9 is characteristic of Th4+ giving rise to incorporation of eight DMSO molecules into the complex cation along with the chloride ion. No structure with this cation has been found earlier, the closest analog is exemplified by the [U(DMSO)7Cl]3+ cation found in the complex salt [U(DMSO)7Cl]Cl3 [12].
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