Reversible addition of tin(II) amides to nitriles.

Lappert's stannylene (Sn[N(SiMe)]) has been reacted with various nitriles, dinitriles and trinitriles with the formation of heteroleptic amidotin(II) amidinates of the general formulae [RC(NSiMe)]SnN(SiMe), R'{[C(NSiMe)]SnN(SiMe)} and R''{[C(NSiMe)]SnN(SiMe)}, where R = Ph (1), 2-(CN)-CH (2), 3-(CN)-CH (3); R' = 1,3-CH (4), 1,4-CH (5) and R'' = 1,3,5-CH (6). The reactions of amidotin(II) benzamidinate 1 with an excess of benzonitrile proceed to homoleptic tin(II) bis(benzamidinate) [PhC(NSiMe)]Sn, which reversibly eliminates benzonitrile and 1 when warmed. The premise of reversibility has been supported by a multinuclear time-dependent NMR study and a theoretical (DFT) description.