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Conformational energies of silacyclohexanes C 5 H 10 SiHMe, C 5 H 10 SiH(CF 3 ) and C 5 H 10 SiCl(SiCl 3 ) from variable temperature Raman spectra
Author(s) -
Kern Thomas,
Hölbling Margit,
Dzambaski Ana,
Flock Michaela,
Hassler Karl,
Wallevik Sunna Ó.,
Arnason Ingvar,
Bjornsson Ragnar
Publication year - 2012
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.3164
Subject(s) - chemistry , enthalpy , raman spectroscopy , ab initio , ab initio quantum chemistry methods , resonance (particle physics) , quantum chemical , nmr spectra database , crystallography , spectral line , analytical chemistry (journal) , computational chemistry , molecule , atomic physics , thermodynamics , organic chemistry , physics , astronomy , optics
From variable temperature vibrational Raman spectra, the axial/equatorial enthalpy differences for the substituted silacyclohexanes C 5 H 10 SiHMe, C 5 H 10 SiH(CF 3 ) and C 5 H 10 SiCl(SiCl 3 ) were determined. The pure liquids and solutions in various solvents were investigated. Preferred conformations are equatorial for methylsilacyclohexane and axial for trifluoromethylsilacyclohexane, consistent with earlier results from nuclear magnetic resonance experiments and ab initio calculations. For C 5 H 10 SiCl(SiCl 3 ) an enthalpy difference close to zero was found, which is supported by high‐level which is supported by high‐level quantum chemical calculations at the second‐order Møller‐Plesset (MP2) and coupled cluster with single, double, and perturbative triple excitations (CCSD(T)) levels, which employed various basis sets. A novel synthesis for C 5 H 10 SiCl(SiCl 3 ) was developed using ClMg(CH 2 ) 5 MgCl instead of BrMg(CH 2 ) 5 MgBr as a starting material. The procedure avoids the formation of partially brominated products, facilitating the purification of the compound. 1 H, 13 C and 29 Si nuclear magnetic resonance data are reported. Copyright © 2012 John Wiley & Sons, Ltd.