THIOPHENE DIOXIDES AND THEIR IRON CARBONYL-COMPLEXES

Thiophen-1,1-dioxide (TDO), which is stable in solution only for a short period, and its (stable) phenyl-substituted derivatives are η4-donor ligands and form complexes with the Fe(CO)3 moiety. In these compounds the CO groups may be replaced stepwise by phosphanes (PMe3, PPh3, PBu3) or phosphites (P(OMe)3, P(OPh)3). Total substitution is possible with Fe(CO)3(η4-TDO). Electronic effects due to substitution can be followed by IR and NMR-spectroscopy. A novel η2-thiophendioxide complex, Fe(CO)2[P(OMe)3]2(η2-TDO), and a compound with a σ-bonded 3-sulfolene-3-yl ligand, FeBr(CO)2[P(OMe)3]2(σ-C4H5SO2), have also been obtained. These compounds and the following three have been characterized by X-ray diffraction: Fe(CO)3(η4-TDO), Fe(CO)3(η4-3,4-diphenylthiophendioxide) and 3a,7a-dihydrobenzo[b]thiophene-1,1-dioxide formed by dimerisation of thiophendioxide and subsequent SO2-elimination. © 1990.