Synthesis, Crystal Structure, and Catalytic Activity of Tricarbonyl Iron Complex Bearing N,N′-bis(2,4,6-trimethylphenyl)ethane−1,2-diimine

Abstract

A tricarbonyliron(0) complex bearing a sterically demanding α-diimine ligand, [Fe(CO)₃(L)] (1) (L = N,N′-bis(2,4,6-trimethylphenyl)ethane-1,2-diimine), was synthesized by the reaction of Fe₂(CO)₉ with L and isolated in 45% yield. Complex 1 was characterized by NMR and IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The crystallographic study revealed that 1 crystallizes in the monoclinic space group P2₁/c and adopts a five-coordinate geometry close to square pyramidal with a τ₅ value of 0.10. The Fe−N bond lengths [1.9185(13) and 1.9285(13) Å] and N−Fe−N bite angle [80.21(5)°] are comparable to those reported for related tricarbonyliron(0) diimine complexes. The structural parameters of the coordinated diimine ligand suggest that it acts as a radical anion rather than as a neutral ligand. In the crystal, no significant hydrogen-bonding or π-stacking interactions are observed, and the crystal packing is maintained mainly through weak intermolecular contacts. The catalytic behavior of 1 toward olefin hydrosilylation was also examined. While no catalytic activity was observed under thermal conditions, photo-irradiation of a mixture of 1-hexene and phenylsilane in the presence of 1 afforded the corresponding hydrosilylation product, (1-hexyl)phenylsilane, in 83% NMR yield.

Graphical abstract

A tricarbonyl iron complex containing a bidentate diimine ligand has been isolated and structurally characterized from the reaction of Fe₂(CO)₉ with N,N′-bis(2,4,6-trimethylphenyl)ethane-1,2-diimine (L)