Sulfur Inversion in and Molecular Structure of <i>meso</i>-3,4-Diethyl-3,4-dimethyl-1-phenyl thiolanium Tetrafluoroborate

Abstract

Abstract Kinetics of sulfur inversion in the title compound was studied by the classical method to afford the following kinetic parameters for the process (1r,3R,4S)→(1s,3R,4S): ΔH\eweq 25.7±0.3 kcal mol−1, ΔS\eweq −2.2±0.8 cal mol−1 K−1. X-Ray crystallography of one isomer (1r,3R,4S) in which the methyl groups are cis to the phenyl group shows some abnormal bond lengths and conformations due to the steric congestion in the 3,4-region of the thiolane ring. The anomalies in the structure are pointed out by comparing the structure with those closely related and the correlation of them with the barrier height to inversion is discussed.