Reactions of ‘pincer’ pyridine dicarbene complexes of Fe(0) with silanes

Abstract

Reactions of Fe(C-N-C)(N₂)₂, 1a, or Fe(C-N^Me-C)(N₂)₂, 1b, C-N-C = 2,6-bis(arylimidazol-2-ylidene)pyridine, C-N^Me-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(η²-H-SiH₂Ph)], 2a, and [Fe(C-N^Me-C)(SiH₂tol)₂(η²-H-SiH₂tol)], 2b, respectively. Complex 1b with excess SiPhH₃ gave [Fe(C-N^Me-C)(SiH₂Ph)₂(H)₂], 3, which was formulated as a dihydride based on the relaxation time T_1(min) in the ¹H-NMR spectra. Reaction of 1a with SiPh₂H₂ gave complex [Fe(C-N-C)(SiHPh₂)₂(η²-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.