Ring size control in diorganotin sulphides by intramolecular SnN coordination

Abstract

The synthesis of intramolecularly coordinated organotin sulphides, [(Me 2N CH 2CH 2CH 2) 2SnS] n ( 1) and [Me 2NCH 2CH 2CH 2Sn(Ph)S] n ( 2), is described. Compounds 1 and 2 are dimers in chloroform solution ( n = 2). Compound 1 forms a centrosymmetric dimer with a planar rectangular Sn 2S 2 four-membered ring in its centre. The tin atoms show a distorted trans- cis- cis octahedral coordination by 2C, 2N and 2S. The tin-nitrogen distances are 2.810(3) and 3.158(5) Å. Compound 1 can be regarded as a model substance for nucleophilic attack at penta-coordinate tin centres. Although the degree of intramolecular coordination of nitrogen to tin is temperature dependent, the four-membered Sn 2Sn 2 ring remains inert in solution. The existence of the asymmetric tin compound (Me 2NCH 2CH 2CH 2) 2SnS 2SnBu t 2 ( 1a) has been characterized in solution.