Redistribution reactions of hydrosilanes mediated by the unsymmetrical and homometallic phosphido-bridged complex (η5-C5Me5) Fe2( CO) 4(μ-CO) (μ-PPh2)

Article abstract of DOI:10.1016/0022-328X(95)00301-6

Reactions of the unsymmetrical and homobimetallic phosphido-bridged complex (η⁵-C5Me5)Fe2(CO)4( μ-CO)(μ-PPh2) (1) with various hydrosilanes gave rise to redistribution of the substituents on hydrosilanes.The reaction of 1 with 2 equiv. of secondary silane R2SiH2 (R = Ph p-Tol) caused effective aryl scrambling to afford a monoarylsilylene-bridged comptex (η⁵-C5Me5)Fe2(CO)4( μ- SiRH)(μ-PPh2) (2, R = Ph; 3, R = p-Tol) and a tertiary silane R3 SiH (R = Ph, p-Tol).The signals of 29Si and 31P<1H) NMR spectra of these complexes appear at very low field (29Si NMR: 2, δ 209.1, ¹J(Si-H) =185 Hz, ²J(Si-P) = 26 Hz; 3, δ 209.1,¹J(Si-H) =185 Hz, ²J(Si-P) = 27 Hz. 31P NMR: 2, δ 224.5; 3, δ 225.0).Complex 2 and Ph3SiH were also formed by the reaction of 1 with 1 equiv. of dihydrodisilane HPh2SiSiPh2H.Similarly the reaction of 1 with alkyldisilane HMe2SiSiMe2H proceeded smoothly to give the alkyl-scrambling product (η⁵-C5Me5)Fe2(CO)4(μ-SiMeH)(μ-PPh2) (4) and Me3SiH.Some intermediates were observed in each reaction by NMR spectroscopy.A reaction mechanism containing silyl(silylene) intermediates is proposed.Keywords: Phosphorus; Iron; Silane; Carbonyl; Cyclopentadienyl; Silylene