Synthetic and Structural Investigations of Linear and Macrocyclic Nickel/Iron/Sulfur Cluster Complexes

Three series of new Ni/Fe/S cluster complexes have been prepared and structurally characterized. One series of such complexes includes the linear type of (diphosphine)Ni-bridged double-butterfly Fe/S complexes [(μ-RS)(μ-SCS)Fe2(CO)6]2[Ni(diphosphine)] (1−6; R = Et, t-Bu, n-Bu, Ph; diphosphine = dppv, dppe, dppb), which were prepared by reactions of monoanions [(μ-RS)(μ-CO)Fe2(CO)6]− (generated in situ from Fe3(CO)12, Et3N, and RSH) with excess CS2, followed by treatment of the resulting monoanions [(μ-RS)(μ-SCS)Fe2(CO)6]−with (diphosphine)NiCl2. The second series consists of the macrocyclic type of (diphosphine)Ni-bridged double-butterfly Fe/S complexes [μ-S(CH2)4S-μ][(μ-SCS)Fe2(CO)6]2[Ni(diphosphine)] (7−9; diphosphine = dppv, dppe, dppb), which were produced by the reaction of dianion [{μ-S(CH2)4S-μ}{(μ-CO)Fe2(CO)6}2]2− (formed in situ from Fe3(CO)12, Et3N, and dithiol HS(CH2)4SH with excess CS2, followed by treatment of the resulting dianion [{μ-S(CH2)4S-μ}{(μ-SCS)Fe2(CO)6}2]2− with (diphosphine)NiCl2. However, more interestingly, when dithiol HS(CH2)4SH (used for the production of 7−9) was replaced by HS(CH2)3SH (a dithiol with a shorter carbon chain), the sequential reactions afforded another type of macrocyclic Ni/Fe/S complex, namely, the (diphosphine)Ni-bridged quadruple-butterfly Fe/S complexes [{μ-S(CH2)3S-μ}{(μ-SCS)Fe2(CO)6}2]2[Ni(diphosphine)]2 (10−12; diphosphine = dppv, dppe, dppb). While a possible pathway for the production of the two types of novel metallomacrocycles 7−12 is suggested, all of the new complexes 1−12 were characterized by elemental analysis and spectroscopy and some of them by X-ray crystallography.