Syntheses, structural characterizations, and heterocumulene metathesis studies of new monomeric bis(triorganosilylamido)tin(II) derivatives

The syntheses and solid-state structures of two new monomeric bis(triorganosilyl)amido stannylenes, bis[N-trimethylsilyl-N-2,6-diisopropylphenylamido]tin(II) (1) and bis[N,N-bis(dimethylphenylsilyl)amido]tin(II) (2), are reported. Heterocumulene metathesis studies reveal that while 1 is inert toward carbon dioxide and isocyanates, 2 undergoes controlled metathesis with these reagents, including a range of para-substituted arylisocyanates, X-C6H4NCO (X = OCH3, CH3, F, Cl, and CF3), that allow for a Hammett investigation of the electronic factors that influence this process. This latter study shows that the rate of tin(II)-mediated heterocumulene metathesis is enhanced by an increased nucleophilicity of the heterocumulene.