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(PPh3)3I. Addition of equivalent amounts of 1 and various dialkynes {RC⋮C−X−C⋮CR (R = H, SiMe3, X = C6H4 (1,4- and 1,3-); R = H, X = SiMe2; R = Ph, X = nothing)} gave polymers 2a−f with varying regiochemical distributions. All polymers were characterized using 1H, 13C, and 29Si 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.