Cyclische Diazastannylene. - XVI : Ringe und Käfige mit Ge(II), Sn(II) und Pb(II)

Abstract

1,3-Di-tert-butyl-2,2-dimethyl-1,3,2,4lambda(2)-diazasilagermetidine (1) and its lead analogue (3), which have been synthesized from the dichlorides of germanium and lead and the dilithium salt of bis(tert-butylamino)dimethylsilane, are compared with the corresponding tin compound 2 in their reactivity towards tert-butylamine. There is a clear dependence of the reaction rate on the nature of the element. The norcubane-like cage Ge3(NtBu)4H2 (5a) and the cubane-like cages Ge4(NtBu)4 (6a) and Pb4(NtBu)4 (6c) result from these reactions. When 3 is treated with bis(methylamino)dimethylsilane, [(Me2Si)2(MeN)3Pb]n (7) precipitates from the reaction mixture. Sn3(NtBu)4H2 (5b) can be transformed into Sn3(NtBu)4Ge (8a) and Sn3(NtBu)4Pb (8b) when heated at high temperatures with 1 or 3, respectively. In these polycyclic compounds two low-valent elements of group IV are simultaneously present in one cage unit. As can be shown, 8b is less stable to bond cleavage than 8a and undergoes redistribution reactions at elevated temperatures to form Sn4(NtBu)4 (6b), Sn2Pb2(NtBu)4 (9), SnPb3(NtBu)4 (10) and Pb4(NtBu)4 (6c).