Pyridine N-oxide promoted hydrosilylation of carbonyl compounds catalyzed by [PSiP]-pincer iron hydrides.

Five [PSiP]-pincer iron hydrides 1–5, [(2-Ph₂PC₆H₄)₂HSiFe(H)(PMe₃)₂ (1), (2-Ph₂PC₆H₄)₂MeSiFe(H)(PMe₃)₂ (2), (2-Ph₂PC₆H₄)₂PhSiFe(H)(PMe₃)₂ (3), (2-(iPr)₂PC₆H₄)₂HSiFe(H)(PMe₃) (4), and (2-(iPr)₂PC₆H₄)₂MeSiFe(H)(PMe₃)₂ (5)], were used as catalysts to study the effects of pyridine N-oxide and the electronic properties of [PSiP]-ligands on the catalytic hydrosilylation of carbonyl compounds. It was proved for the first time that this catalytic process could be promoted with pyridine N-oxide as the initiator at 30 °C because the addition of pyridine N-oxide is beneficial for the formation of an unsaturated hydrido iron complex, which is the key intermediate in the catalytic mechanism. Complex 4 as the best catalyst shows excellent catalytic performance. Among the five complexes, complex 3 was new and the molecular structure of complex 3 was determined by single crystal X-ray diffraction. A proposed mechanism was discussed. [ABSTRACT FROM AUTHOR]