Synthesis and characterisation of hexacarbonyl 2-phenylethene-1,1-dithiolatodiiron

2-Phenylethenethione (1) and its tautomer (1′) were prepared by reaction of ethynyl benzene with S8. The reaction of the tautomer with triiron dodecacarbonyl in dry toluene led to the formations of a classic triiron cluster, [Fe3(μ3-S)2(CO)9] (2), and a novel diiron complex, [Fe2(μ-S)2CCHPh)(CO)6] (3). In this complex, the bridging linkage, 2-phenylethene-1,1-dithiolate, was formed during the reaction involving both C–S bond formation and cleavage. Complex 3 was fully characterised including X-ray single crystal diffraction analysis. In its solid state, the neighboring phenyl rings are within the distance of π–π stacking interaction. Its electrochemistry was carried out in both dicholormethane (DCM) and acetonitrile. It was found that the reversibility was severely affected by solvent. The complex exhibited improved reversibility in the nonpolar solvent (DCM).