Observed and calculated vibrational spectrum of trans-tetrachlorobispyridinesilicon(IV) and related species

Abstract

Raman spectroscopic studies on SnCl₄,2NMe₃ and SnCl₄,2N(CD₃)₃ are used to define a ‘tin–nitrogen stretching vibration.’ By applying the force constant obtained for the Sn–N bond to SiCl₄,2py and PCl₅,py (py = pyridine) computed data are compared with the observed Raman and i.r. spectra. From vibrational data alone it is not possible to assign cis- or trans-stereochemistry to the adduct SiCl₄,2py. The species SiCl₃⁺,3py and SiCl₂²⁺,4py are examined spectroscopically and assignments of stereochemistry are proposed. The compound SiH₂I₂,4py is examined spectroscopically and a 1 : 3 adduct of SiCl₃I with pyridine is characterised. Previous assignments on Sil₄,4py, PPh₅, and PCl₄⁺,2py are criticised.