Electronic and steric properties of stable silylene ligands in metal(0) carbonyl complexes

A series of stable silylene–transition metal complexes have been synthesized by substitution of silylenes 1 and 2 for carbonyl ligands in simple metal carbonyl complexes: M(1)2(CO)4 and M(2)2(CO)4 (M=Cr, Mo, W), Fe(1)(CO)4 and Ru(1)2(CO)3. X-ray crystal structures are reported. Infrared and NMR spectroscopy were used to probe the electronic properties of stable silylene ligands. Based on these data, the stable silylene 1 behaves electronically very much like triaryl phosphines.