Organosilicon chalcogenides with trisilane units – bicyclo[3.3.1]nonanes, bicyclo[3.2.2]nonanes and spiro[4.4]nonanes

Treatment of 1,2,3-trichloropentamethyltrisilane (1) with H2S/NEt3 results in the formation of a mixture of two isomers of (Me5Si3)2S3 with a bicyclo[3.3.1]nonane (2a) and a bicyclo[3.2.2]nonane (2b) skeleton, while the reaction of 1 with Li2Se yields one product only, (Me5Si3)2Se3 (3a), with a bicyclo[3.3.1]nonane structure. Besides 1H, 13C, 29Si and 77Se NMR spectroscopy 3a has also been characterized by a crystal structure analysis. Compounds Si(SiMe2EMR2E)2 (5a–h: MR2: SiMe2 (5a, c, d), SiPh2 (5b), GeMe2 (5e, f), SnMe2 (5g, h); E=S (5a, b, e, g), Se (5c, f, h), Te (5d)) with a spiro[4.4]nonane skeleton have been obtained in mixture with varying amounts of the corresponding six-membered rings (R2ME)3 by reactions of mixtures of 1,2,2,3-tetrachlorotetramethyltrisilane (4) and diorganodichlorosilanes, Me2GeCl2 or Me2SnCl2, with H2S/NEt3, Li2Se or Li2Te and have been characterized in situ by multinuclear NMR spectroscopy (1H, 13C, 29Si, 119Sn, 77Se, 125Te) and GC-MS.