Poly{ferrocene(phenylene)bis(silylenevinylene)}s via Platinum- and Rhodium-Catalyzed Hydrosilylation of Diethynylbenzenes with 1,1‘-Bis(dimethylsilyl)ferrocene

Abstract

Ferrocene-containing polymers with one and two ferrocenes per repeat unit have been prepared via hydrosilylation polymerization of dialkynes and ferrocene-containing bis-enynes with 1,1‘-bis(dimethylsilyl)ferrocene ( 1 ) using Karstedt's catalyst (platinum-divinyltetramethyldisiloxane) and Rh(PPh 3 ) 3 I. Addition of equivalent amounts of 1 and various dialkynes {RC⋮C−X−C⋮CR (R = H, SiMe 3, X = C 6 H 4 (1,4- and 1,3-); R = H, X = SiMe 2; R = Ph, X = nothing)} gave polymers 2a − f with varying regiochemical distributions. All polymers were characterized using 1 H, 13 C, and 29 Si NMR spectroscopy, MALDI-TOF mass spectrometry, and elemental analyses. Novel ferrocene-containing bis-enynes ( 4a, b ) were prepared by hydrosilylation addition of 1 to 2 equiv of 1,4-bis(trimethylsilyl)butadiyne and 1,4-bis(trimethylsilylethynyl)benzene, respectively. Desilylation of 4a, b gave ferrocene-containing bis(enyne)s ( 5a, b ) that were used as monomers for the synthesis of polymers with two ferrocenes per repeat unit ( 6a, b ). The X-ray crystal structure of the bis(enyne) 4a has also been described, and the redox behavior of polymers 2a − e (Pt), 2a (Rh), and 2c (Rh) were studied using cyclic voltammetry. In all cases a single reversible redox wave was observed, attributed to the Fe(II)−Fe(III) redox couple of the ferrocene center.