Bis(amido)diazadiarsetidinide and Amido(imino)arsenide Complexes of Divalent Metals

The Mg and Ca complexes of the tert-butyl substituted bis(amido)diazadiarsetidinides [{(tBuNAs)(2)(tBuN)(2)}M(thf)(2)] (M=Mg (1), Ca (6)) were prepared by addition of nBu-secBuMg or [{(p-tBu)(C6H4)CH2}(2)Ca] to [(tBuNAs)(2)(tBuNH)(2)] (Ia). Upon evaporation of coordinating THF, 1 is selectively converted to the amido(imino)arsenide complex [Mg{As(NtBu)(2)}(2)] (2) whereas 6 decomposes to several products under these conditions. Hydrolysis of 2 with H2O yields the hitherto unknown compound As(NHtBu)(3) (3) whereas hydrolysis of Ia leads to the formation of the oxygen bridged bis(amidodiazadiarsetidine) [O{(tBuNH)(tBuNAs)(2)}(2)] (4). Reaction of 2 with 3 yields the heteroleptic Mg complex with an amido(imino)arsenide and a bis(amido)diazadiarsetidinide ligand [{(tBuNAs)(2)(NHtBu)(NtBu)}Mg{As(NtBu)(2)}] (5). The homologous Ca compound (7) was obtained by conversion of Ia with Ca(hmds)(2) (hmds=N(SiMe3)(2)). Finally, the tetrylene complexes [E{(tBuNAs)(2)(tBuN)(2)}] (E=Ge (8), Sn (9), Pb (10)) were prepared by either conversion of Ia with E(hmds)(2) for E=Sn, Pb or by addition of the dichlorides of Ge and Sn to [(tBuNAs)(2)(tBuNLi)(2)] (Ib). All compounds were characterised by NMR and IR spectroscopy, mass spectrometry and single crystal x-ray diffraction for 1, 2, 4, 5, 6 and 10.