Photoreactions of silyliron(II) complexes Cp*Fe(CO)2SiMe3 (Cp* = η5-C5H5, η5-C5Me5) in the presence of trihydrosilanes

Article abstract of DOI:10.1016/0022-328X(92)83224-6

The photochemistry of silyliron(II) complexes Cp^*Fe(CO)2SiMe3 (Cp^* = η⁵-C5H5, η⁵-C5Me5) in the presence of trihydrosilanes is described.Three types of products were observed, depending on the bulkiness of the Cp^* ligands and the substituents on the trihydrosilanes: (η⁵-C5H5)Fe(CO)2SiMe3 reacts with tert-alkylsilanes RSiH3 (R = ^tBu, C(Me2)2H) upon irradiation to give silylene-bridged diiron complexes (η⁵-C5H5)2Fe2(CO)3(μ-SiHR) in good yields.In contrast, (η⁵-C5Me5)Fe(CO)2SiMe3 reacts with the tert-alkylsilanes photochemically to give silyl monoiron complexes (η⁵-C5Me5)Fe(CO)2SiH2R exclusively.Using p-TolSiH3 instead of tert-alkylsilane, the main photolysis product was the hydridobis(silyl)iron complex Cp^*Fe(CO)SiMe3(H)SiH2-p-Tol.The X-ray crystal structure analysis of (η⁵-C5H5)2Fe2(CO)3(μ-SiH^tBu) revealed that this complex adopts a geometry in which the two Cp rings and a Si-H bond are located on the same side with respect to the SiFe2C four-membered ring 29Si NMR spectra of the silylene-bridged diiron complexes showed signals at remarkably low field (δ 235.5-289.1 ppm).A mechanism for the formation of these silylene-bridged diiron complexes is proposed.