Reactivity of an amidinato silylene and germylene toward germanium(II), tin(II) and lead(II) halides

The coordination chemistry of an amidinato silylene and germylene toward group 14 element(II) halides is described. The reaction of the amidinato silicon(II) amide [LSiN(SiMe3)(2)] (1, L = PhC(NtBu)(2)) with SnCl2 and PbBr2 afforded the amidinato silylene-dichlorostannylene and -dibromoplumbylene adducts [L{(Me3Si)(2)N}SiEX2] (E = Sn, X = Cl (2); E = Pb, X = Br (3)), respectively, in which there is a lone pair of electrons on the Sn(II) and Pb(II) atoms. X-ray crystallography, NMR spectroscopy and theoretical studies show conclusively that the Si(II)-E(II) bonds are donor-acceptor interactions. Similar electronic structures were found in the amidinato germylene-dichlorogermylene and -dichlorostannylene adducts [L{(Me3Si)(2)N} GeECl2] (E = Ge (5), Sn (6)), which were prepared by treatment of the amidinato germanium(II) amide [LGeN(SiMe3)(2)] (4) withGeCl(2).dioxane and SnCl2, respectively.