Synthesis and Properties of s-Alkyl-Substituted Silanediyl-Bridged and Silanetriyl-Bridged Diiron Complexes,Cp2(CO)2Fe 2(μ-CO)[μ-Si(X)CHR2] and Cp2(CO) 2Fe2(μ-CO)[μ-Si(DMAP)CHR2]+I -(X = H, I; R = Et, Ph; DMAP = 4-(Dimethylamino)pyridine)

Article abstract of DOI:10.1246/bcsj.70.2193

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.