Vibrational spectra and assignments, conformational stability, and ab initio calculations of cyclopropylmethyl silanes

Abstract Vibrational spectra (3500 to 50 cm −1 ) of gaseous, liquid and solid and the samples trapped in an Ar matrix of cyclopropylmethylsilane, c-C 3 H 5 -CH 2 SiH 3 , and cyclopropylmethyltrifluorosilane, c-C 3 H 5 -CH 2 SiF 3 , have been recorded. The spectra of the gaseous and liquid phases have been interpreted on the basis of the predominance of a conformation having a gauche structure (>90%) and this form exists exclusively in the solid. Only for cyclopropylmethyltrifluorosilane was there evidence for a second conformer.