Synthesis and characterisation of aromatic ethynyl-bridged ferrocenes

A series of aromatic ethynyl-bridged ferrocenes with the general formula Fc–CC–R–CC–Fc (Fc=ferrocenyl, R=C6H2(-p-CH3)2 (1), C6H4-p-C6H4 (2), C5H3N (3), 9,10–C14H8 (4), C4H2S (5), (C4H2S)2 (6) and (C4H2S)3 (7)) has been synthesised by the reaction of ethynyl ferrocene with the appropriate dibromo-arenes. The new complexes have been characterised by spectroscopic techniques. The structures of 3 and 7 were determined via X-ray crystallography, and both show the trans–trans configuration of the two ethynyl ferrocene groups with respect to the central R group. The electronic properties of the compounds have been studied via optical spectroscopy and cyclic voltammetry.