Spectra and structure of small ring compounds. XXXVII. Two-dimensional potential surface and barrier to interconversion for silacyclopentane

The Raman spectrum of gaseous silacyclopentane has been recorded from 25 to 4000 cm−1. The series of Q branches observed at 264.5, 259.9, and 255.3 cm−1 have been assigned as the fundamental and hot bands of the radial vibration of a hindered pseudorotator. A two-dimensional potential surface has been determined and indicates that the interconversion between equivalent twisted forms proceeds through a puckered intermediate. The barrier of 1414 cm−1 is of the same order as that found using a one-dimensional treatment, and the two models are discussed.