Hydrosilylation of Ferrocenylalkyne−Dicobalthexacarbonyl Complexes. Model Reactions for the Synthesis of Organometallic Dendrimers

Regio- and stereoselective hydrosilylation reactions of ferrocenylalkyne−dicobalthexacarbonyl complexes with HSiEt3 or dendrimer Si[CH2CH2CH2Si(CH3)2H]4 have afforded the ferrocenylvinylsilanes [FcC(SiEt3)CH2] (1), [FcCCC(SiEt3)C(H)R] [R = Fc (E-4), H (13), SiMe3 (Z-15)], and [(E)-FcC(H)C(SiEt3)CCSiMe3] (14) and the ferrocenylvinyl-functionalized carbosilane dendrimers Si[CH2CH2CH2Si(CH3)2C(Fc)CH2]4 (3) and (Z)-Si[CH2CH2CH2Si(CH3)2C{CCFc}C(H)Fc]4 (6). Characterization of all compounds by 1H, 13C{1H}, and 29Si{1H} NMR and IR spectroscopy, as well as mass spectrometry, supports their assigned structures. The molecular structures of compounds [{Co3(CO)9}(μ3-CCH2Fc)] (2), [C(O)C(Fc)C(SiEt3)CC(H)Fc] (5), [{Co2(CO)6}(μ,η2-FcCCCCH)] (8), and [{Co2(CO)6}2(μ,η2,η2-FcCCCCSiMe3)] (9) have been determined by single-crystal X-ray diffraction. The redox activity of the model diferrocenylalkynyl complex 4 and the corresponding octaferrocenyl dendrimer 6 has been examined by cyclic voltammetry.