The synthesis and characterization of complexes obtained from the reactions between Li[N-t-Bu(SiMe3)] (A) or the sodium analogue Na[N-t-Bu(SiMe3)] (B) and the cyanoarene RCN (R = Ph or 4-MeOC6H4) are discussed. These are the THF adduct [Li{µ-cis-N(t-Bu)C(Ph)N(SiMe3)}(THF)]2 (1), the TMEDA adduct Li[N(t-Bu)C(Ph)N(SiMe3)](TMEDA) (2), the neutral ligand-free lithium benzamidinate Li[N(t-Bu)C(C6H4OMe-4)N(SiMe3)] (3), and the THF adduct Li[N(t-Bu)C(C6H4OMe-4)N(SiMe3)](THF) (3a). The preparation and structure of the crystalline compound [Na{µ-cis-N(t-Bu)C(Ph)N(SiMe3)}(OEt2)]2 (4) is described. From the lithium benzamidinate 1 and Sn(II) chloride the tin(II) complex [Sn{N(t-Bu)C(Ph)N(SiMe3)}2] (5) was obtained. The molecular structures of the crystalline compounds 1, 4, and 5 were established by X-ray diffraction. In 1 and 4 the benzamidinato ligand is both chelating and bridging, with the Me3Si-substituted nitrogen atom as the bridging site. The central planar (MN)2 four-membered ring is a rhombus in 1, with almost equal LiN bond lengths, whereas in 4 the bonds to Na(1) are significantly longer than those to Na(2). In 5, the ligand is N,N′-chelating. Key words: alkali metals, tin(II), benzamidinates, NMR spectra, X-ray structures.
