Reactions of 'pincer' pyridine dicarbene complexes of Fe(0) with silanes.

Reactions of Fe(C-N-C)(N2)2, 1a, or Fe(C-NMe-C)(N2)2, 1b, C-N-C = 2,6-bis(arylimidazol-2-ylidene)pyridine, C-NMe-C = 2,6-bis(arylimidazol-2-ylidene)-3,5-dimethylpyridine, aryl = 2,6-iPr2C6H3, with silanes are described. Complex 1a with excess SiPhH3 and complex 1b with excess Si(tol)H3, Ph = phenyl, C6H5, tol = 2-methylphenyl, gave the complexes [Fe(C-N-C)(SiH2Ph)2(2-H-SiH2Ph)], 2a, and [Fe(C-NMe-C)(SiH2tol)2(2-H-SiH2tol)], 2b, respectively. Complex 1b with excess SiPhH3 gave [Fe(C-NMe-C)(SiH2Ph)2(H)2], 3, which was formulated as a dihydride based on the relaxation time T1(min) in the 1H-NMR spectra. Reaction of 1a with SiPh2H2 gave complex [Fe(C-N-C)(SiHPh2)2(2-H2)], 4, while reaction with Si(mes)H3 gave complex [Fe(C-N-C)(SiH2mes)2(N2)], 5, mes = mesityl, 2,4,6-trimethylphenyl. The comparison of the reactivity with other pincer complexes of iron and the mechanism leading to 2a-5 are discussed.