SYNTHESIS AND STRUCTURES OF BIS(AMINO)GER MA AND BIS(AMINO)STANNA CHALCOGENIDES

The cyclic bis(amino)germylene 1 and the -stannylene 2 react with elem ental S, Se and Te to yield oxydation products of the general formula Me2Si(NtBu)2MEl2M(NtBu)2SiMe2 (M = Ge, El = S (4), El = Se (5), El = T e (6); M = Sn, El = Se (9), El = Te (10)). As may be deduced from X-ra y structures (4, 5, 6, 9, 10) all compounds show similar central skele tons: the three spirocyclicly connected four-membered rings SiN2M (2x) and MEl2M are oriented in an orthogonal way to oneanother. The german ium and the tin atoms thus are in a distorted tetrahedral coordination while the chalcogen atoms only have two neighbours in acute angles. I f 1 is allowed to react with trimethylamine-N-oxide, the oxygen is tra nsferred to germanium and [Me2Si(NtBu)2GeO]3 (3) is formed. Contrarily to the other compounds 3 can be described as a trimer. There is a cen tral almost planar Ge3O3 six-membered ring, the germanium atoms servin g as spiro-cyclic centres to three GeN2Si four-membered rings (X-ray s tructure of 3). In the central four-membered rings of 4, 5, 6, 9 and 1 0 no transanular bonding between the chalcogen atoms have to be consid ered although these atoms have small distances to oneanother. The mean M-El distances have been found to be: Ge-O 1.762(5), Ge-S2.226(3), Ge -Se2.363(3), Ge-Te2.592(5), Sn-Se 2.536(3), Sn-Te 2.741(3) angstrom.