Influence of intramolecular Sn–chalcogen interactions on the conformational preferences for three diorganotin(IV) xanthates

The influence of intramolecular Sn–chalcogen interactions on the stability of different coordination possibilities available for three diorganotin(IV) xanthates [Me2Sn(MeOCS2)2 (1), Ph(Me)Sn(MeOCS2)2 (2) and Ph2Sn(MeOCS2)2 (3)] by means of theoretical methods is presented herein. A comparison of results obtained at the RHF level of theory employing STO3G, 3-21G∗∗ and augmented triple zeta quality basis sets developed for relativistic pseudopotentials is shown. RHF-STO3G all-electron calculations followed by fourth order Møeller–Plesset calculations were carried out in order to study the effect of electron correlation. It was observed that the use of correlation consistent basis sets yielded stability trends which reflect previous observations for similar xanthate molecular systems. The stabilization of the above conformers is assessed through an NBO analysis and the calculation of energy barriers by potential energy surface scans for the conformational changes. The approach described herein improves the theoretical results obtained in [M.I. Mohamed-Ibrahim, S.S. Chee, M.A. Buntine, M.J. Cox, E.R. Tiekink, Organometallics 19 (2000) 5410], where these three compounds were originally reported. It was concluded that secondary bonding in these compounds is best described by means of the computational paradigm herein described.