Bi- and triferrocene complexes containing silylenevinylenephenylene bridges. Model compounds for Poly{ferrocene(phenylene)bis(silylenevinylene)}s

A series of conjugated ferrocene-based organosilicon complexes with one, two, or three ferrocene units have been prepared via hydrosilylation of alkynes with ferrocenylsilanes using Karstedt's catalyst (platinum-divinyltetramethyldisiloxane) and Rh(PPh3)(3)I. Reaction of 1,1 '-bis(dimethylsilyl)ferrocene (1) with 2 equiv of RC equivalent to CR1 (R = H, R-1 = Ph, SiMe3, Fc {Fc = (eta-C5H5)Fe(eta-C5H4)}; R = SiMe3, R-1 = Ph, Fc) gave Fe[(eta(5)-C5H4)(Me)(2)SiC(R)=CHR1](2) complexes (type 1) with varying regiochemical distributions. Addition of 2 equiv of dimethylsilylferrocene (2) to dialkynes R-C equivalent to C-X-C equivalent to C-R [R = H, X = C6H4 (1,4- and 1,3-), SiMe2; R = Me, X = Fc ' J{Fc ' = (eta-C5H4)Fe(eta-C5H4)}; R = SiMe3, X = C6H4 (1,4- and 1,3-); R = Ph, X = nothing] resulted in Fc(Me)(2)Si(R)C=C(H)-X-(H)C=C(R)Si(Me)(2)Fc complexes (type 2), again with varying regiochemical distributions. The platinum-promoted hydrosilylations resulted in beta-(E) and alpha-regioisomers, whereas the rhodium-catalyzed reactions gave primarily beta-(Z) species with minor amounts of the beta-(E) isomer. X-ray crystallographic studies of the predominant adducts obtained from 1 and Me3SiC equivalent to CPh as well as 2 and Me3Si-C equivalent to C-C6H4-C equivalent to C-SiMe3 (1,4-) using Karstedt's catalyst are described. Cyclic voltammetry shows single redox waves for most systems indicative! of no interaction between the Fe-Fe centers. One complex, Fc(Me)(2)Si(C=CH2)-Fc '-Si(C=CH2)(Me)(2)Fc, shows two reversible waves for the two different types of ferrocene center.