Stereochemical non-rigidity of complexes of hypercoordinate Group 14 elements

Negrebetsky, Vadim V.; Tandura, S. N.; Baukov, Yuri I.

doi:10.1070/rc2009v078n01abeh003888

Cited by 65 publications

(29 citation statements)

References 189 publications

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“…A distinguishing feature of hypervalent compounds is their stereochemical nonrigidity, which manifests itself as a permutational isomerization around the silicon atom (e.g., ). In other words, the isomerization of this type consists in the intramolecular process of interconversion between isomers, that is, ligand‐site exchange.…”

Section: Introductionmentioning

confidence: 99%

“…Various mechanisms have been advanced to explain the ligand‐site exchange in the hypervalent compounds . A unified mechanism seems to be lacking.…”

Section: Introductionmentioning

confidence: 99%

“…For our purposes an important point is that the experiments have provided a considerable body of data on permutational isomerization . The ligand‐site exchange is a stereodynamic process; its rate ranges from 10 −1 to 10 −5 s . Therefore, these processes are conveniently studied by using the dynamic nuclear magnetic resonance (NMR) spectroscopy (an examination of coalescence phenomena and that of the temperature dependence of the line shape).…”

Section: Introductionmentioning

confidence: 99%

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Ligand‐site exchange in intramolecular complexes of silicon: substituent effects

Кузнецова

Egorochkin

Negrebetsky

et al. 2012

J of Physical Organic Chem

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The intramolecular complexes containing coordination bonds Si←N or Si←O are distinguished for their stereochemical nonrigidity resulting in interconversion between isomers, that is, ligand‐site exchange. The influence of the substituents bound to the silicon atom on the free energies of activation for ligand exchange ΔG≠ of specific interest is poorly understood. In this work, the literature data on substituent influence on the energies ΔG≠ for 13 series of the complexes have been considered, using the correlation analysis. On the basis of the obedience of the energies ΔG≠ to the linear free energy relationship, it has been established for the first time that the ΔG≠ values depend not only on the inductive and resonance effects but also on the polarizability and steric effects of substituents. The reason for the occurrence of the polarizability effect is the appearance of excess charges on Si and N (or O) atoms as a result of intramolecular coordination consisting in the charge transfer from the donor center (N or O atom) to the acceptor one (Si atom). In some series the contribution of the polarizability or steric effect to the overall change in ΔG≠ because of the influence of substituents is a maximum. An understanding of these effects may give a better insight into the mechanism of nucleophilic substitution, involving organoelement compounds. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

“…Various mechanisms have been advanced to explain the ligand‐site exchange in the hypervalent compounds . A unified mechanism seems to be lacking.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ligand‐site exchange in intramolecular complexes of silicon: substituent effects

Кузнецова

Egorochkin

Negrebetsky

et al. 2012

J of Physical Organic Chem

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“…The Ge(1)-O(1) bond in the isolated molecule 5a is somewhat stronger than those in the isolated molecules of the complexes with the GeCl 3 fragment. 11 The change in the Ge (1) (in 5a•6MeCN), despite a large number of such interactions (6)(7)(8)(9)(10)(11). In corporation of an H 2 O molecule into the solvate cluster 3a•6MeCN resulted only in insignificant increase (to 6.3 kcal mol -1 ) of the overall energy of the interactions involving bromine atoms.…”

Section: Methodsmentioning

confidence: 95%

Tribromogermyl monochelates — derivatives of N,N-disubstituted 2-hydroxycarboxylic amides

et al. 2010

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Reactions of GeBr 4 with N,N dimethyl 2 trimethylsiloxypropionamide (2a), (S) 2 trime thylsiloxypropionpyrrolidide ((S) 2b), and N,N dimethyl O (trimethylsilyl)mandelamide (2c) afforded pentacoordinated neutral (O,O) monochelates, viz., N,N dimethyl 2 tribromoger myloxypropionamide (3a), (S) 2 tribromogermyloxypropionpyrrolidide ((S) 3b), and N,N di methyl O (tribromogermyl)mandelamide (3c), respectively. X ray diffraction study was per formed for tribromides 3a, (S) 3b, and 3c, as well as for the N,N dimethylmandelamide (1c) described earlier. According to the X ray diffraction data, the Ge atom in tribromides 3a, (S) 3b, and 3c is pentacoordinated and has trigonal bipyramidal configuration with two halo gen atoms and oxygen atom of the ether group in the equatorial positions and the halogen atom and the amide oxygen atom in the axial fragment, the bonds in which are somewhat longer as compared to the analogous bonds in tetracoordinated Ge compounds.

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“…Of special interest are the studies of formation of the solvate complexes of organyltrifluorosilanes having tetra‐ and pentacoordinate silicon atom, their specific and nonspecific solvation and solvolytic reactions . There are at least two reasons for such interest: first, a plethora of intramolecular silicon complexes show substantial variation of the IR and NMR spectroscopic characteristics of the coordination site as a function of the aggregate state, temperature and the nature of the solvent . Second, since chemical reactions are mostly carried out in solution, understanding of the processes occurring upon interaction of the molecules of organyltrifluorosilanes with the solvent will promote the progress of synthetic chemistry and materials based on organosilicon compounds.…”

Section: Introductionmentioning

confidence: 99%

Effect of proton donors on the intramolecular coordination C=O→Si-F in (acyloxymethyl)trifluorosilanes.Ab initio,DFT and FTIR study, QTAIM analysis

Chípanina

Lazareva

Aksamentova

et al. 2014

J. Phys. Org. Chem.

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The intramolecular С=O→Si coordination in H‐complexes of (acetoxymethyl)trifluorosilane and (benzoyloxymethyl)trifluorosilane with proton donors HCl, PhOH, MeOH, and CHCl3 was investigated by density functional theory and second‐order Møller‐Plesset perturbation theory (MP2) methods. Interrelation and mutual influence of the intramolecular coordination bond С=O→Si and intermolecular hydrogen bonds C=O···H and Si–F···H in H‐complexes was established using the AIM and NBO analyses. The С=O→Si coordination is weakened by the C=O···H hydrogen bonding but enhanced by the Si–Fax···H hydrogen bonding. The structure of H‐complexes of (acetoxymethyl)trifluorosilane with proton donors in solution was determined by comparing the ν(C=O) and ν(Si–F) frequencies calculated using the conductor‐like polarizable continuum model and their experimental Fourier transform infrared values. Copyright © 2014 John Wiley & Sons, Ltd.

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Stereochemical non-rigidity of complexes of hypercoordinate Group 14 elements

Cited by 65 publications

References 189 publications

Ligand‐site exchange in intramolecular complexes of silicon: substituent effects

Ligand‐site exchange in intramolecular complexes of silicon: substituent effects

Tribromogermyl monochelates — derivatives of N,N-disubstituted 2-hydroxycarboxylic amides

Effect of proton donors on the intramolecular coordination C=O→Si-F in (acyloxymethyl)trifluorosilanes.Ab initio,DFT and FTIR study, QTAIM analysis

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