Reactivity of [Fe2(CO)6(μ-CO)(μ-dppm)] towards unsaturated sulfur-containing compounds, SO2, CS2 and ArNCS: facile carbon–sulfur bond cleavage at the diiron centre

Photolysis of [Fe2(CO)6(μ-CO)(μ-dppm)] (1) with SO2, CS2 and ArNCS leads to the formation of [Fe2(CO)6(μ-SO2)(μ-dppm)] (2), [Fe4(CO)10(μ3-S)(μ-CS)(μ-dppm)2] (3), [Fe2(CO)3(CNAr){μ-SC(NAr)C(O)S}(μ-dppm)] (4–5) and [Fe2(CO)4{μ-SC(N-p-tolyl)C(O)S}(μ-dppm)] (6), respectively. Complex 2 is a simple CO substitution product, while in 3 carbon–sulfur cleavage and coupling of diiron units has occurred. Dithiolate-bridged 4–6 also result from carbon–sulfur bond cleavage of one isothiocyanate and coupling of the sulfur with CO and a second isothiocyanate. Two isomers of complexes 3–6 are found and in thiolate-bridged 4–6 these interconvert as a result of inversion at the imine nitrogen, which has been monitored by VT NMR.