The molecular and electronic structure of the electron transfer series [Fe2(NO)2(S2C2R2)3]z (z = 0, -1, -2; R = phenyl, p-tolyl, p-tert-butylphenyl)

Three dinuclear (nitrosyl)iron complexes containing three 1,2-di(phenyl)ethylene-1,2-dithiolate ligands have been prepared ([Fe-2(NO)(2)(S2C2R2)(3)](0) (R = phenyl, 1a; p-tolyl, 2a; (4-tert-butyl)phenyl, 3a)). Each of these compounds represents the first member of a three-membered electron-transfer series: [Fe-2(NO)(2)(S2C2R2)(3)](z) (z = 0, -1, , -2). The salt [Co(Cp)(2)][Fe-2(NO)(2)(L-3)(3)] has also been isolated. The molecular structures of 2a and 3a have been determined by X-ray crystallography. Both neutral complexes contain two nearly linear FeNO units, one of which is S,S'-coordinated to two dithiolene ligands yielding a square-based pyramidal Fe(NO)S-4 polyhedron; the second FeNO moiety forms two (mu(2)-S)-bridges to the first unit and is S,S'-coordinated to a third dithiolate radical yielding also a square-based pyramidal Fe(NO)S-4 polyhedron. The electronic structures of the neutral, monoanionic, and dianionic species have been elucidated spectroscopically (UV-vis, IR, EPR, Mossbauer): [{Fe-II(NO+)}(L-center dot){Fe-II(center dot O)}(L)(2)](0) (S = 0); [{Fe-II(center dot O)}(L-center dot){Fe-II(center dot O)}(L)(2)](1-) (S = (1)/(2)); and [{Fe-II(center dot O)}(L){Fe-II(center dot O)}(L)(2)](2-) (S = 0), where (L)(2-) represents the corresponding closed-shell dithiolate dianion and (L-center dot)(-) is its monoanionic radical.