Photolysis of 2 molar amounts of CpFe(CO)2SiMe3 (= FpSiMe3 1) with s-alkylsilanes R2CHSiH3 (2a: R = Et; 2b: R = Ph) produces the silylene (or silanediyl)-bridged diiron complexes Cp2(CO)2Fe2(μ-CO)[μ-Si(H)CHR2] (3a: R = Et; 3b: R = Ph) which exist mainly in cis-form. The treatment of cis-3 with an excess amount of CH2I2 stereoselectively affords the iodosilylene-bridged diiron complexes Cp2(CO)2Fe2(μ-CO)[μ-Si(I)CHR2] (4a: R = Et; 4b: R = Ph) in cis-form. The reaction of complexes 4 with 4-(dimethylamino)pyridine (=DMAP) gives the base-stabilized silylyne (or silanetriyl)-bridged diiron complexes Cp2(CO)2Fe2(μ-CO)[μ-Si(DMAP)CHR 2]+I- (5a: R = Et; 5b: R = Ph) in 35 and 43% yields, respectively. The cis-trans isomerization of complexes 3 was studied under thermal and photochemical reaction conditions. The molar ratios of the cis and trans isomers of complexes 3 in the thermal equilibrium at 50 °C were 95 : 5 (3a) and 78 : 22 (3b), respectively, and in the photostationary state at 10 °C were 80 : 20 and 30 : 70, respectively. The structures of complexes 3b and 4b have been characterized by X-ray diffraction.
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