Formation and characterization of cyclic and polycyclic silthianes containing SiSi bonds

The reactions of several organochlorosilanes and -oligosilanes with H2S and NEt3 have been investigated. Different bicyclic silthianes with bis-cyclopentyl, bicyclo-[3,3,0]-octane, bicyclo-[2,2,1]-heptane (norbornane), bicyclo-[3,2,1]-octane, bicyclo-[2,2,2]-octane and bicyclo-[3,2,1]-nonane skeletons were formed and have been characterized by MS and 1H-, 13C- and 29Si-NMR. The reaction of 1,1,2,2-tetrachlorodimethyldisilane with H2S and NEt3 yields 1,3,5,7,9,11-hexamethyl-1,3,5,7,9,11-hexasila-2,4,6,8,10,12-hexathiatetracyclo-[5,5,03,11,05,9]-dodecane (4c) containing three disilane units. Density functional theory calculations proved the general observation that compounds with Si3S2 five-membered rings are preferred. The crystal structures of 4c, 1,3,3,5,7,7-hexamethyl-1,3,5,7-tetrasila-2,4,6,8-tetrathiabicyclo-[3,3,0]-octane (6) and 1,2,2,4,4,5,6,6,8,8-decamethyl-1,2,4,5,6,8-hexasila-3,7-dithiabicyclo-[3,3,0]-octane (9) have been determined.