ISSN:
1573-8779
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract 3,3-Dimethyl-1-oxa-3-silacyclopentane was synthesized, and its molecular structure was determined by gas phase electron diffractometry using ab initio calculations (GAUSSIAN-92, RHF method, 6-31G* basis set). The six models derived from the gas phase electron diffraction analysis equally adequately (R≈3%) describe experimental data, whereas quantum chemical calculations lead to only one (O-envelope) conformer. The stereochemical data and the results of ab initio calculations confirm that the O-envelope is the best conformation; its geometrical parameters are as follows (bond lengths ra in Å, and angles in degrees; total error in parentheses in units of the least significant digit): r(Si-Ccyc) 1.891(3) and 1.904; r(Si-CMe) 1.877 and 1.879; r(C-C) 1.556(7); r(C-O) 1.431(3) and 1.445; r(Ccyc-H) 1.11(2); r(CMe-H) 1.10(2); ϕ(O−C−C−Si) −33.0(14); ∠CcycSiCcyc 92.2(5); −33.0(14); ∠CMeSiCMe 107.2(8); ∠SiCC 102.6(6); ∠CCO 109.9(11); ∠HCcycH 110.5(47); ∠SiCMeH 111.6(14). Method for the synthesis of 3,3-dimethyl-1-oxa-3-silacyclopentane is given, and generalized notation for five-membered ring confor-mations is suggested.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02437172
Permalink