TY - JOUR
T1 - Diastereomeric hexacoordinate silicon complexes
T2 - Preparation, structure and epimerization
AU - Girshberg, Olga
AU - Kalikhman, Inna
AU - Stalke, Dietmar
AU - Walfort, Bernhard
AU - Kost, Daniel
N1 - Funding Information:
Support for this work from the German Israeli Foundation for Scientific Research and Development (GIF), grant I-628-58.5/1999 is gratefully acknowledged. We thank Dr Michael Borshchevsky for solving the differential equations for exchange in the unequally-populated signal system.
PY - 2003/12/16
Y1 - 2003/12/16
N2 - The synthesis of a neutral hexacoordinate silicon complex (6) with a chiral silicon and an adjacent chiral carbon center, via an intramolecular nucleophilic displacement, is described. 6 exists in a mixture of two diastereomers. One of the diastereomers has been characterized by an X-ray crystallographic analysis, and is found to have a nearly octahedral geometry about the silicon. 6 undergoes two intramolecular ligand-site exchhange processes, observable by NMR spectroscopy: reversible dissociation of the N-Si dative bond, leading to interchange of the N-methyl groups (ΔG*=16. 7±0.2kcalmol-1 at 365 K), and inversion of configuration at the silicon center, measured by selective inversion recovery NMR spectroscopy (21.0kcalmol-1 at 350 K).
AB - The synthesis of a neutral hexacoordinate silicon complex (6) with a chiral silicon and an adjacent chiral carbon center, via an intramolecular nucleophilic displacement, is described. 6 exists in a mixture of two diastereomers. One of the diastereomers has been characterized by an X-ray crystallographic analysis, and is found to have a nearly octahedral geometry about the silicon. 6 undergoes two intramolecular ligand-site exchhange processes, observable by NMR spectroscopy: reversible dissociation of the N-Si dative bond, leading to interchange of the N-methyl groups (ΔG*=16. 7±0.2kcalmol-1 at 365 K), and inversion of configuration at the silicon center, measured by selective inversion recovery NMR spectroscopy (21.0kcalmol-1 at 350 K).
KW - Hypercoordination
KW - Inversion of configuration
KW - Molecular rearrangement
KW - Selective inversion recovery NMR
KW - Silicon
UR - http://www.scopus.com/inward/record.url?scp=0842349349&partnerID=8YFLogxK
U2 - 10.1016/j.molstruc.2003.07.017
DO - 10.1016/j.molstruc.2003.07.017
M3 - Article
AN - SCOPUS:0842349349
SN - 0022-2860
VL - 661-662
SP - 259
EP - 264
JO - Journal of Molecular Structure
JF - Journal of Molecular Structure
IS - 1-3
ER -