New complexes with MSiO or MSiS linkages (M=Fe or Co)

Ph2XSiFe(CO)2Cp [X=p-tolylS (1a), MeO (1b)] and Ph[2-MeOC6H4]XSiFe(CO)2Cp [X=Cl (2a), OMe (2b)] have been fully characterised, including X-ray crystal structure determinations for 1a, 1b and 2a. None of the examples showed any tendency for migration of the X groups from silicon to iron, with elimination of silylene. However, very ready loss of the X groups was seen in the electrospray mass spectra, suggesting formation of the cationic silylene–iron complex ions is favoured. This was especially so for 2a and 2b, where intramolecular stabilisation of the silicon centre from the 2-OMe group is possible. The stable siloxane O[SiPh2{Co(CO)4}]2 was also characterised; the X-ray crystal structure analysis shows a SiOSi bond angle of 153°.