Iron Pyridine-2-thiolate Complexes: Interconversion of [Fe0(CO)4(SC5H4N)]-, cis-[FeII(CO)2(SC5H4N)2], and [FeII(SC5H4N)3]-

The reaction of bis(2-pyridyl) disulfide with [HFe(CO) 4 ] - affords [Fe(CO) 4 (SC 5 H 4 N)] -, in which the pyridine-2-thiolate ligand is bound in a monodentate (S-bonded) mode. Oxidative addition of bis(2-pyridyl) disulfide to [Fe(CO) 4 (SC 5 H 4 N)] - and concomitant displacement of [SC 5 H 4 N] - leads to the neutral monomeric compound cis -[Fe(CO) 2 (SC 5 H 4 N) 2 ]. In the presence of [SC 5 H 4 N] - in CH 3 CN at 60 °C, cis -[Fe(CO) 2 (SC 5 H 4 N) 2 ] undergoes facile conversion to d 6 Fe(II) high-spin [Fe(SC 5 H 4 N) 3 ] - . Reduction of cis -[Fe(CO) 2 (SC 5 H 4 N) 2 ] and [Fe(SC 5 H 4 N) 3 ] - under CO at room temperature with [BH 4 ] - /[Na][benzophenone] affords the monodentate (S-bonded) complex [Fe(CO) 4 (SC 5 H 4 N)] - . The results are consistent with sulfur-donor atom stabilization of the lower oxidation states of iron, while the S,N-chelating pyridine-2-thiolate ligand enhances the stability of iron in the higher oxidation state.