Synthesis of Mono- and Diiron Dithiolene Complexes as Hydrogenase Models by Dithiolene Transfer Reactions, Including the Crystal Structure of [{Ni(S2C2Ph2)}6]

The dithiolene transfer reaction between the nickel bis(dithiolene) complex [Ni(S2C2Ph2)2] and iron carbonyls has been re-investigated, and the conditions for the production of the dinuclear product [Fe2(μ-S2C2Ph2)(CO)6] have been optimized. Interception of a purple intermediate, thought to be [Fe(CO)3(S2C2Ph2)], in the reaction of [Fe(CO)5] with [Ni(S2C2Ph2)2] by the addition of PPh3 affords the new dark blue mononuclear complex [Fe(CO)2(PPh3)(S2C2Ph2)] in good yield. The fate of the nickel dithiolene fragments in these reactions has also been established by crystallographic characterization of the hexamer [{Ni(S2C2Ph2)}6] and the trinuclear cluster [Ni3(μ-S2C2Ph2)3(PPh3)2]. The substitution reactions of [Fe2(μ-S2C2Ph2)(CO)6] with PPh3 in the presence of Me3NO to give monosubstituted [Fe2(μ-S2C2Ph2)(CO)5(PPh3)] and disubstituted [Fe2(μ-S2C2Ph2)(CO)4(PPh3)2] are also reported.