A DFT Study - Wiley Online Library

DOI: 10.1002/slct.201702912 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

Full Papers

z Electro, Physical & Theoretical Chemistry

Strategic Design and Utilization of Molecular Flexibility for Straddling the Application of Organic Superbases: A DFT Study Ajeet Singh,*[a, b] Animesh K. Ojha,[a] and Hyun Myung Jang[b] The density functional theory (DFT) calculations were performed for a series of new molecular frameworks that have potential to work as organic superbases. In the present report, we have exploited and strategically substituted 2 and 6 positions of the pyridine by a potential anchoring group, 1,5,7triazabicyclo[4.4.0]dec-5-ene (TBD). The value of proton affinities (PAs) of the molecular frameworks was calculated in the gas phase as well as in acetonitrile solution. The designed nonionic and neutral organic superbases were found to have higher basicity than that of the benchmarked molecule, 1,8-bis (dimethylamino)-naphthalene (DMAN). The zero-point vibrational energy (ZPVE) and PAs values were calculated for the designed molecular frameworks at B3LYP/6-311 + G**//B3LYP/6-

Introduction Discovery of DMAN (1,8-bis(dimethylamino)-naphthalene) has reopened a new venture to design and synthesize new organic superbases.[1,2] The tremendous interest shown by the scientific community in this subject is due to the role of proton in chemistry and bio-chemistry, particularly, in the proton transfer reactions.[3] Non-ionic, neutral and very low nucleophilic tendency of organic superbases are important aspects in organic synthesis and therefore these are being extensively studied during recent years.[4,5] Tailoring of PA values along with its various potential applications in different fields e. g. storage of gases and catalytic applications always trigger to the scientific community to design and synthesize of new organic superbases.[5] The applications of organic superbases vary from organic synthesis to green chemistry owing to the fact that they have diverse and dynamic qualities, in terms of better solubility, required mild reaction conditions, produce less chemical waste because it is recyclable at the same time.[4,6] After the discovery of DMAN, most of the organic superbases

[a] Dr. A. Singh, Dr. A. K. Ojha Department of Physics Motilal Nehru National Institute of Technology Allahabad Allahabad-211004, India E-mail: [email protected] [b] Dr. A. Singh, Prof. H. M. Jang Division of Advanced Materials Science Pohang University of Science and Technology (POSTECH) Pohang 790-784, Republic of Korea Supporting information for this article is available on the WWW under https://doi.org/10.1002/slct.201702912

ChemistrySelect 2018, 3, 837 – 842

Wiley VCH 1802 / 105242

31 + G* level of theory. For compression, we have also performed the optimization of all the structures at M06-2X/6311 + G**//M06-2X/6-31 + G* level of theory. The molecular framework 9 has highest PAs values 1151.2 and 1246.3 kJ mol1 in the gas phase and in acetonitrile solution, respectively at B3LYP/6-311 + G**//B3LYP/6-31 + G* level of theory. The designed molecular frameworks have better flexibility, which enables it for selective extraction of the smaller to larger size molecules by varying the size of the cavity, as required for the various applications. In this context, we have explored the application of designed molecular frameworks for the selective extraction of UO22 + over VO2 +.

are based on naphthalene framework related structure.[5g] However, the recent studies revealed that the molecular framework other than benzene based framework will also work as strong organic superbases.[7] In the gas phase, the reported PA value of DMAN was 1031.2 kJ mol1.[2] In general, the DMAN’s PA value is accepted as a threshold value for the super basicity and considered as a benchmark in the superbase chemistry. Designing of new molecular frameworks and testing of their different physical and chemical properties using theory would have become only possible due to the availability of computational modeling and more sophisticated theory such as, DFT that includes electron correlation in the calculations for such organic molecules. In the quest for new organic superbases, the designing of new molecular framework instead of naphthalene based framework is always encouraging for the scientific community due to its own importance.[8] Recent study revealed that the strong cationic resonanceassisted hydrogen bonding upon protonation and proper placement of adjacent functional groups are the key point for designing of new organic superbases.[9] However, it is to note that all those organic superbases are having the sterically hindered environment around the protonation site, which limits the applications of the organic superbases in many cases. DMAN is well known sterically hindered organic superbase, however, this superbase has no application in CO2 assimilation due to its limited flexibility. Thus, flexible organic superbases have own advantages over the sterically hindered organic superbases.[1,9] Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. Structurally, it is similar to the 837

2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Montag, 15.01.2018 [S. 837/842]

1

Full Papers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

benzene, with one methine group (= CH-) replaced by a nitrogen atom. A unique combination of two 1,5,7-triazabicyclo [4.4.0]dec-5-ene (TBD) molecules placed at 2 and 6 positions of pyridine, respectively leads to organic superbases that have larger flexibility and its synthetic route is also known in the literature (Scheme 1).[10]

Scheme 1. Structures of pyridine 1, DMAN 2, TBD 3, of pyridine substituted TBD and designed frameworks of organic superbases 5–9.

tively. Also, in equation, B and BH + denote the base and its conjugate acid, respectively. Further, we have employed solvent effects into account by means of the polarizable continuum model (PCM)[14] through single-point energy calculations done at the B3LYP/6-311 + G** level of theory (using the gas-phase optimized geometries). The internal reaction coordinate (IRC) and transition state (TS) calculations were performed at B3LYP/ 6-31 + G* level of theory. Molecular electrostatic potential (MESP) calculations (see supporting information) have also been done for the newly designed frameworks at B3LYP/6-31 + G* level of theory.[15] The pKa values of designed frameworks were calculated by using the standard thermodynamic cycle[16– 19] and the related formula and the detail calculations procedures are given in supporting information. Further, we have performed the optimization of UO22 +, VO2 + with superbases 7 and UO22 +, VO2 + with acrylamidoximes, by using LANL2DZ basis set by using effective core potential (ECP) for uranium and vanadium atoms and 6–31 + G* basis set for the rest of the atoms which provides better results for relativistic corrections for the transition metals.[20] We have also performed separate calculations for the determining the interaction energy (Eint) of UO22 +, VO2 + with superbase 7 by using M06-2X/6-31 + G* level of theory. Following equation was used to calculate the Eint: DEint ¼ EðcomplexÞ - EðsuperbaseÞ - EðUO2 2þ or VO2 þ Þ

In this article, we are reporting newly designed molecular frameworks that differs from the known organic superbases in terms of flexibility. These frameworks may be considered as an adjustable spanner. In the quest of new molecular framework as an organic superbase, we have designed molecular frameworks that grasp smallest (like proton) and larger molecules, e. g. VO2 + and UO22 + in the same molecular framework. The designed frameworks have higher PA value compared to the benchmark molecule DMAN, and at the same time these are (5–7) have the higher affinity for UO22 + compared to VO2 +.

Computational Methodology All the structures were optimized using Gaussian 09 program[11] package, Becke’s exchange functional (three-parameter) with the correlation functional of Lee, Yang and Parr (B3LYP)[12] and basis set 6–31 + G* was used.[13a] Single-point calculations were also performed by adding the polarization function with higher basis set (6-311 + G**). For comparison, we have also performed the optimization of all the structures at M06-2X/6-311 + G**// M06-2X/6-31 + G* level of theory.[13b,c,d] Harmonic vibrational frequency calculations were also done at the same level of theory to confirm that the optimized structures are at the minima of the potential energy surface; as it is characterized by the presence of positive vibrational frequencies. Zero-point vibrational energies were computed at the B3LYP/6-31G* level of theory. The PAs values[13e] are calculated at the B3LYP/6-311 + G**//B3LYP/6-31 + G* level of theory using the general equation, PA(B) = DEel + DZPVE, where (DEel) = [E(B) - E(BH +)] and (DZPVE) = [ZPVE(B) - ZPVE(BH +)]. Where, DEel and DZPVE are the electronic and the zero-point vibrational energies, respecChemistrySelect 2018, 3, 837 – 842

Wiley VCH 1802 / 105242

where E(Complex) is the energy of organic superbase complex with UO22 + or VO2 +.

Results and discussion Quantum chemical based calculations are extremely powerful tool for the designing of novel organic superbases.[9] The values of PA of 1–9 frameworks (Table 1) were calculated at the B3LYP/

Table 1. The calculated proton affinities at B3LYP/6-311 + G**//B3LYP/631 + G* level of theory for 1–9 in the gas phase and in acetonitrile solution using CPCM continuum model. For pKa calculations, solvation model based on density (SMD) were used. Gas phase energies are ZPVE corrected in kJ mol1. The proton affinities calculated in acetonitrile are ZPVE corrected and in kJ mol1. Sr. no.

Gas phasea

Acetonitrilea

pKa

1 2 3 4 5 6 7 8 9

919.8 1031.2b 1046.9 [1050.6] 1082.5 1106.1 1107.3 1129.9 1138.4 1151.2

1124.0 1197.3 1209.3 1210.5 1213.0 1214.1 1236.8 1238.3 1246.3

12.8 (12.3)c 17.8 (18.5)d 25.6 (26.0)e 27.4 31.9 32.1 34.2 35.7 37.1

[a] Zero-point energy corrected. [b] Experimental value: 1030.1 kJ/mol (from ref. 1). [c,d,e] J. Phys. Chem. Ref. Data, 1998, 27, 413.

6-311 + G**//B3LYP/6-31 + G* level of theory (Scheme I) employing DFT methods. The appropriateness of used basis set 838


Montag, 15.01.2018 [S. 838/842]

1

Full Papers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

was cross checked by calculating all the parameters for a known molecule 2 at same level of theory and it was found that the results obtained by the used basis set are very close to the experimental value.[21] The calculated values of PA’s for 5–9 at M06-2X/6-311 + G**//M06-2X/6-31 + G* level of theory were found to be consistent with those calculated PAs at B3LYP/6311 + G**//B3LYP/6-31 + G* level of theory (see supporting information). Further, the calculated values of PA of 5 and 9 at PBE/6-311 + G**// PBE/6-31 + G* level of theory do not differ much with those calculated at B3LYP/6-311 + G**//B3LYP/631 + G* level of theory (Table 2). However, the small changes in

Table 2. Proton affinity values calculated at different levels of theory for the designed framework 5 and 9 in the gas phase. Energies are ZPVE corrected in kJ mol1. Sr. No.

B3LYP/6-311 + G**// B3LYP/ 6-31 + G*

M06-2X/6-311 + G**// M06-2X/6-31 + G*

PBE/6-311 + G**// PBE/6-31 + G*

5 9

1106.1 1151.2

1108.11 1143.13

1102.21 1146.26

PAs values at two different level of theories can be explained by considering the nature of protonated species.[5f] The protonated N….N distances (Table 3) are shorter in case of the

Table 3. Calculated geometric parameters of free bases and their conjugate acids at the B3LYP/6-31 + G* level. Complex 2+

UO2 VO2 +

7

Acrylamidoximes

600.2 196.5

174.2 165.3

closed species (8 and 9) than that of simple species (5, 6 and 7) therefore the proton that is present in between two nitrogens behave differently in protonated species. The calculated barrier for proton transfer indicate that when we move from simple species (5, 6 and 7) to cyclic species (8 and 9), the proton transfer barrier energy varies from higher to lower values. The calculated results indicate that for the species 8 and 9, the proton transfer become barrierless (see supporting information). In such cases (8 and 9), the dispersion forces are predominant at the protonated site which is well reflected in the values calculated at M06 level of theory.[21b,5f] The isodesmic reaction setup[5g] was used for the calculations of strain energy (SE) of unprotonated bases and the cumulative effect i. e. hydrogen bonding plus strain energy (HB + SE) + (see supporting information). The isodesmic reaction provides a qualitative information regarding nature of interaction and therefore it should not be used in a quantitative sense. However, it is very useful for predicting the factors responsible for enhanced basicity of the molecules.[5h] The role of computational chemistry for the designing of new and novel organic superbase molecular frameworks has become more useful since the Alder’s discovery.[1] In order to ChemistrySelect 2018, 3, 837 – 842

Wiley VCH 1802 / 105242

examine the basicity of the designed molecules, we have performed theoretical studies on 5–9 newly designed molecules by calculating the unprotonated and protonated species in the gas phase and acetonitrile solution. The calculated PAs values of the designed frameworks in gas as well as in solvent phase acetonitrile are presented in Table 1 along with their respective pKa values. It is worthy to note that the gas phase value of PA for DMAN 2 calculated in the present study (1031.2 kJ mol1) is in good agreement with the experimentally observed value (1030.0 kJ mol-1).[2a] The above values within the chemical accuracy of ~ 1.0 kJ mol1, which lends the credibility of calculated values in the present study. The value of PA for the monoprotonation of 5 turns out to be 1106.3 kJ mol1. This is considerably higher PA value compared to the benchmark molecule DMAN. In Table 1, we have listed the calculated values of PA against the name of designed molecular frameworks based on TBD and pyridine systems. The values of PA of the designed framework vary from 1106.3 to 1151.2 kJ mol1 . Such a high value of PA is attributed by the strong cationic resonance within the central guanidine moiety and enhanced through the cooperative multiple intramolecular hydrogen bonding (Figure 1). The calculated value of PA of TBD 3 turns out to be 1046.9 kJ mol 1 and its pKa value is found to be 25.6 in acetonitrile.[22] Further, the designed molecules (5–9) have high PAs and pKa values. The high values of PAs and pKa may be due to the fact that the co-operative effect between the two TBD units wherein the protonation of one unit induces a partial protonation in the second one through a strong intermolecular hydrogen bond (IMHB). The proton shuttles back and forth between the protonation sites, however, in case of 8 and 9 it is almost barrierless process which is quite evident by looking at the results of TS calculations (see supporting information)[5f] The true TS were confirmed by intrinsic reaction coordinate (IRC) path by allocation of proton on forward and backward position (see supporting information Figure S2). Pyridine has a basic character, however, it has not been considered in superbase category due to the fact that it’s PAs and pKa values are less compared to the PAs and pKs values of DMAN. However, when we move form pyridine to substituted pyridine at 2 position with TBD, the values of PAs and pKa were found higher than that of the DMAN. Further, when we substitute the 2 and 6 positions of pyridine with TBD, a dramatic change in the values of PAs and pKa were observed. In case of designed framework 5, the one arm of TBD flips in opposite side. However, it is a flexible structure and having low energy barrier. To prevent the flipping of the TBD arm, we have introduced the -OH group at suitable position on TBD. The -OH group prevents the flipping of the arm via formation of hydrogen bond (see supporting information, figure S5). Further, we have extended the formation of hydrogen bonds by substituting another arm of the TBD unit with -OH group that further forms the hydrogen bond and restrict the free rotation of the arms. The effect of hydrogen bonding is also reflected in the PAs and pKa values when we move from 6 to 8. Looking at the geometry, it is interesting to note that after protonation of one 839


Montag, 15.01.2018 [S. 839/842]

1

Full Papers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

Figure 2. The optimized structure of 7:UO22 + (a)and 7:VO2 + (b) using LANL2DZ for uranium, vanadium atom using effective core potential basis sets (ECP) and B3LYP/6-31 + G* for the rest atom [Gray = carbon; blue = nitrogen; white = hydrogen; light gray = vanadium; red = oxygen; cyan = uranium].

Figure 1. B3LYP/6-31 + G* optimized geometries of 1–9 and their corresponding conjugate acids [Gray = carbon; blue = nitrogen; white = hydrogen; Red = oxygen].


Wiley VCH 1802 / 105242

TBD, it forms intramolecular hydrogen bonds[23] with nitrogen of another TBD provided that the pyridine nitrogen is more closer compared to the TBD nitrogen. It can be confirmed by performing intramolecular proton transfer barrier by calculating TS and subsequently IRC calculations of protonated species. The TS and IRC calculations (5-9) clearly indicate that the intramolecular hydrogen bond is formed with the neighbouring TBD unit however, the pyridine nitrogen is in the interactive position (see supporting information). Further, to see the influence on pKa and PAs values by the adjoining of two TBD units via nitrogen and carbon atoms, we further extended our calculations for the next designed frameworks 8 and 9. The calculated results indicate that, when we adjoin the two TBD units, further improvement in the pKa and PAs values is observed. In the unprotonated form of the molecular framework 8 and 9, the distance between two TBD ˚ , respectively. The nitrogens are found to be 2.75 and 2.77 A difference in distances between two TBD nitrogen are explained in terms of framework 8 that bridges with nitrogen atom while framework 9 bridges with the carbon atom. Further, nitrogen is being smaller in size and having a lone pair of the electron, it is more suited for resonance than that of the carbon. Upon protonation of 8 and 9, the NH….N distance is ˚ , respectively. This geometrical data found to 1.74 and 1.75 A indicates that 8 should have higher PA value than that of 9. After a close analysis of the geometrical parameters, the NH….N linearity in 9 is higher than that of 8 (see Table 3). This observation could reasonably explain the marginal increase of PA value of 9 than that of 8. Further, the calculated SE and (hydrogen bonding + strain energy) contribution of hydrogen bonding also revealed that a little variation can change the different energy contributions (see supporting information). The calculated MESP also indicates that the most negative potential point is located in between the two TBD moieties (see supporting information). The values calculated at B3LYP/6-31 + G*//B3LYP/6-311 + G** level of theories indicate that the designed 2 and 6 substituted pyridine systems possess higher basicity than that of DMAN and therefore it can also be used as an efficient tool for the selective extraction, organic synthesis, green chemistry etc.[1 3] Therefore we have also explored the possibility of these 2 and 6 substituted pyridine superbases in an effective and 840


Montag, 15.01.2018 [S. 840/842]

1

Full Papers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

selective extraction of UO22 + over VO2 +. The UO22 + and VO2 + are available in sea water and their selective extraction is very tedious. To explore the possible applications of designed frameworks, we have performed theoretical calculations for selective extraction of UO22 + over VO2 +. For this purpose, we have taken a designed framework 7. We have selected this framework 7 since it has a sufficient flexibility and at the same time, it also possess higher PA value. The calculated interaction energy (Table 4) with 7:UO22 + is

Table 4. Interaction energy with 7:UO22 +, 7:VO2 + and with acrylamidoximes molecule at LANL2DZ using effective core potential basis sets (ECP) for uranium, vanadium atom and B3LYP/6-31 + G* for the rest of the atoms. The calculated interaction energy values are given in kcal mol1. Sr. no.

1 1H + 2 2 H+ 3 3 H+ 4 4 H+ 5 5 H+ 6 6 H+ 7 7H + 8 8H + 9 9 H+

Bond length (A˚) r(N…..H) + r(N….N)

r(N….H)

Bond angle (0) (N—H…..N)

2.83 2.64 2.97 2.62 3.15 4.00 3.11 3.99 3.51 2.75 2.61 2.77 2.63

1.59 1.76 2.23 2.23 2.54 1.74 1.75

157.5 138.27 147.89 142.16 158.43 137.4 138.3

1.01 1.01 1.11 1.02 1.03 1.02 1.02 1.04 1.04

Conclusions In the present work, we have designed few novel molecular frameworks that have less strain and more flexible arms compared to the existing organic superbases. Flexibility enables them to behave as an adjustable spanner. Such designed molecular frameworks can adjust itself to grasp the smallest as well as larger size molecules. We have shown that a neutral organic superbase can grasp smallest (proton) as well as larger molecule (UO22 +) by the same molecule framework. The designed pyridine substituted TBD based organic superbases have PA value 1151.2 kJ mol1 at the B3LYP/6-31 + G*//B3LYP/6311 + G** level of theory. The DFT calculated results indicate that such pyridine substituted TBD systems can act as organic superbases. Provided that the usual applications of organic superbases, the first time we have explored a new and possible application of designed organic superbases in the selective extraction of UO22 + over the VO2 +.

Acknowledgements A. Singh thanks DST-SERB, India, for a “Young Scientist Start-up Research Grant” (Project grant: SB/FT/CS-127/2014). A. Singh and H. M. Jang also thank to POSTECH for the support of this research work.

Conflict of Interest The authors declare no conflict of interest. Keywords: Density functional theory (DFT) · Proton affinities · pka · Organic superbases · Selective extraction

sufficiently high than that of 7:VO2 +. To compare the efficiency of designed systems, we have calculated the interaction energy with known system i. e. acrylamidoximes.[24] The calculated results revealed that the acrylamidoximes have higher interaction energy with UO22 + than that of VO2 +. This result is nicely corroborated with the experimental report.[24] The designed systems have higher interaction energy difference than that of the known selective extractor of UO22 +. Further, the optimized structure of 7:UO22 + and 7:VO2 + indicates that the oxygen plays important role for the effective interaction. Further the TBD nitrogen lone pair seems to play an important role for strong interaction with UO22 + than that of VO2 +.[25] An another interesting result was found with VO2 + wherein only one TBD nitrogen effectively interacts, while another nitrogen moves away from the interactive position (see supporting information). The geometrical arrangement of the two TBD arms behave differently upon interaction with UO22 + and VO2 + and this is why the structure of VO2 + become bent and looks like Vshaped structure while UO22 + is only slightly deviated from the linearity during optimization.


Wiley VCH 1802 / 105242

[1] R. W. Alder, P. S. Bowman, R. W. S. Steele, D. R. Winterman, Chem. Commun. 1968, 0, 723–724. [2] a) Y. K. Lau, P. P. S. Saluja, P. Kebarle, R. W. Alder, J. Am. Chem.Soc. 1978, 100, 7328–5459; b) R. W. Alder, Chem. Rev. 1989, 89, 1215–1223; c) D. Margetic´, Physico-Chemical Properties of Organosuperbases, in Superbases for Organic Synthesis: Guanidines, Amidines, Phosphazenes and Related Organocatalysts (ed T. Ishikawa), 2009, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470740859.ch2. [3] R. P. Bell , The Proton in Chemistry, Cornell University Press, Ithaca, New York, 1973. [4] H. Oediger, F. Mçller, K. Eiter, Synthesis 1972, 591–598. [5] a) Y. Hirono, K. Kobayashi, M. Yonemoto, Y. Kondo, Chem. Commun. 2010, 46, 7623–7624; b) K. Vazdar, R. Kunetskiy, M. S. J. Saame, M. S. K. Kaupmees, I. Leito, U. Jahn, Angew. Chem. Int. Ed. 2014, 53, 1435–1438; c) R. Lo, B. Ganguly, J. Phys. Chem. C 2014, 118, 6680–6689; d) A. K. Biswas, R. Lo, M. K. Si, B. Ganguly, Phys. Chem. Chem. Phys. 2014, 16, 12567–12575; e) R. Lo, A. Singh, M. K. Kesharwani, B. Ganguly, Chem. Commun. 2012, 48, 5865–5867; f) M. P. Coles, P. J. Aragn-Sez, S. H. Oakley, P. B. Hitchcock, M. G. Davidson, Z. B. Maksic´, R. Vianello, I. Leito, I. Kaljurand, D. C. Apperley, J. Am. Chem. Soc. 2009, 131, 16858–16868; g) A. Singh, B. Ganguly, New J. Chem. 2009, 33, 583; h) S. T. Howard, J. Am. Chem. Soc. 2000, 122, 8238–8244; i) J. F. Kçgel, D. Margetic´, X. Xie, L. H. Finger, J. Sundermeyer, Angew. Chem., Int. Ed. 2017, 56, 3090; j) D. Baric´, B. Kovacˇevic´, Tetrahedron lett. 2016, 57, 442; k) J. F. Kçgel, X. Xie, E. Baal, D. Gesevicˇius, B. Oelkers, B. Kovacˇevic´, J. Sundermeyer, Chem. -A Eur. J. 2014, 20, 7670–7685. [6] a) E. D. Raczyn´ska, J. Gal, P. Maria, Chem. Rev. 2016, 116, 13454–13511; b) K. Khamaru, B. Ganguly, RSC Advanc. 2015, 5, 102247–102255.

841


Montag, 15.01.2018 [S. 841/842]

1

Full Papers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

[7] a) A. Singh, B. Ganguly, New J. Chem. 2008, 32, 210–213; b) A. Singh, B. Ganguly, J. Phys. Chem. A. 2007, 111, 6468–6471; c) E. Estrada, Y. SimonManso, Angew. Chem., Int. Ed. 2006, 45, 1719–1719; d) D. Eric, N. H. Lambert, J. Am. Chem. Soc. 2015, 137, 10246–15651; e) A. Singh, S. Chakraborty, B. Ganguly, Eur. J. Org. Chem. 2006, 21, 4938–4942; f) R. J. Schwamm, R. Vianello, A. Marsˇavelski, M. A. Garcia, R. M. Claramunt, I. Alkorta, J. Saame, I. Leito, C. M. Fitchett, A. J. Edwards, M. P. Coles, J. Org. Chem. 2016, 81, 7612–7625; g) D. Baric´, B. Kovacˇevic´, J. Phys. Org. Chem 2016, 29, 750–758; h) D. Margetic´, T. Ishikawa, T. Kumamoto, Eur. J. Org. Chem. 2010, 2010, 6563–6572; i) D. Margetic, P. Trosˇelj, T. Ishikawa, T. Kumamoto, Bull. Chem. Soc. Jpn. 2010, 83, 1055–1057; j) N. Suzuki, K. Kishimoto, K. Yamazaki, T. Kumamoto, T. Ishikawa, D. Margetic´, Synlett 2013, 24, 2510–2514. [8] a) R. J. Schwamm, R. Vianello, A. Marsˇavelski, M. . Garca, R. M Claramunt, J. Org. Chem. 2016, 81, 7612–7625; b) D. Ewa, Raczyn´ska, J. Gal, P. Maria, Chem. Rev. 2016, 116, 13454–13511. [9] a) A. F. Pozharskii, Russ. Chem. Rev. 1998, 67, 1–24; b) Z. B. Maksic´, B. Kovacˇevic´, R. Vianello, Chem. Rev. 2012, 112, 5240–5270. [10] F. Krçhnke, F. W. Krçck, Chem Ber. 1971, 104, 1645–1654. [11] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09, Gaussian, Inc., Wallingford CT, 2009. [12] a) A. D. Becke, J. Chem. Phys. 1993, 98, 5648–5652; b) C. Lee, W. Yang, R. G. Parr, Phys. Rev. B 1988, 37, 785–789. [13] a) W. J. Hehre, L. Radom, P. v. R Schleyer, J. A. Pople, Ab initio Molecular Orbital Theory, Wiley, New York, 1988; b) Y. Zhao, D. G. Truhlar, J. Chem.


Wiley VCH 1802 / 105242

[14]

[15] [16] [17]

[18] [19] [20] [21]

[22] [23] [24]

[25]

Theory Comput. 2011, 7, 669–676; c) D. Margetic´, I. Antola, New J. Chem. 2016, 40, 8191–8193; d) K. Zhang, D. M. Zimmerman, A. Chung-Phillips, C. J. Cassady, J. Am. Chem. Soc. 1993, 115, 10812–2415. a) J. Tomasi, M. Persico, Chem. Rev. 1994, 94, 2027–2094; b) M. Cossi, V. Barone, R. Cammi, J. Tomasi, Chem. Phys. Lett. 1996, 255, 327–335; c) V. Barone, M. Cossi, J. Tomasi, J. Chem. Phys. 1997, 107, 3210–3221; d) V. Barone, M. Cossi, J. Tomasi, J. Comput. Chem. 1998, 19, 404–417; e) M. Cossi, V. Barone, J. Chem. Phys. 1998, 109, 6246–6256. K. D. Sen, P. Politzer, J. Chem. Phys. 1989, 90, 4370–4372. D. M. Camaioni, C. A. Schwerdtfeger, J. Phys. Chem. A 2005, 109, 10795– 9345. a) I. A. Topol, G. J. Tawa, S. K. Burt, A. A. Rashin, J. Phys. Chem. A 1997, 101, 10075–10085; b) A. A. Magill, K. J. Cavell, B. F. Yates , J. Am. Chem. Soc. 2004, 126, 8717–8724. A. V. Marenich, C. J. Cramer, D. G. Truhlar, J. Phys. Chem. B 2009, 113, 6378–6396. J. Tomasi, B. Mennucci, E. Cancs, J. Mol. Struct.: THEOCHEM 1999, 464, 211–226. a) C. J. Cramer, D. G. Truhlar, Phys. Chem. Chem. Phys. 2009, 11, 10757– 10816; b) P. J. Hay, Faraday Discuss. 2003, 124, 69–83. a) S. H. Oakley, M. P. Coles, P. B. Hitchcock, Inorg. Chem. 2004, 43, 7564– 7566; b) N. Mardirossian, M. Head-Gordon, J. Chem. Theory Comput. 2016, 12, 4303–4716. E. P. Hunter, S. G. Lias, J. Phys. Chem. Ref. Data 1998, 27, 413–656. D. Baric´, I. Dragicevic´, B. Kovacˆevic, J. Org. Chem. 2013, 78, 4075–4082. a) P. S. Kelley, P. S. Barber, P. H. K. Mullins, R. D. Rogers, Chem. Commun. 2014, 50, 12504–12507; b) C. Yang, S. Pei, B. Chen, L. Ye, H. Yua, S. Hub, Dalton Trans. 2016, 45, 3120–3129. M. A. Lashley, A. S. Ivanov, V. S. Bryantsev, S. Dai, R. D. Hancock, Inorg. Chem. 2016, 55, 10818–10829.

Submitted: December 1, 2017 Revised: December 28, 2017 Accepted: December 28, 2017

842


Montag, 15.01.2018 [S. 842/842]

1