Synthetic and Structural Characterization of Linear and Macrocyclic Ni/Fe/E (E = S, Se) Cluster Complexes

Three new series of (diphosphine)Ni-bridged butterfly Fe/E (E = S, Se) cluster complexes have been prepared and structurally characterized. One such series of complexes includes the linear type of (diphosphine)Ni-bridged double-butterfly Fe/E complexes [(μ-RSe)(μ-S═CS)Fe2(CO)6]2[Ni(diphosphine)] (1–8, R = n-Bu, Ph; diphosphine = dppe, dppv, dppb, dppp, dppf). These complexes were prepared by one-pot reactions of the monoanion [(μ-RSe)(μ-CO)Fe2(CO)6]− (generated in situ from Fe3(CO)12, RSeH, and Et3N) with excess CS2 followed by treatment of the resulting monoanion [(μ-RSe)(μ-S═CS)Fe2(CO)6]− with (diphosphine)NiCl2. The second and third series include the macrocyclic type of (diphosphine)Ni-bridged quadruple- and double-butterfly Fe/E complexes [{μ-Se(CH2)3Se-μ}{(μ-S═CS)Fe2(CO)6}2]2[Ni(diphosphine)]2 (9a–11a, diphosphine = dppe, dppv, dppb) and [μ-Se(CH2)3Se(CH2)3Se-μ][(μ-S═CS)Fe2(CO)6]2[Ni(diphosphine)] (9b–11b, diphosphine = dppe, dppv, dppb), respectively. While macrocycles 9a–11a were produced by one-pot reactions of the dianion [{μ-Se(CH2)3Se-μ}{(μ-CO)Fe2(CO)6}2]2– (formed in situ from Fe3(CO)12, HSe(CH2)3SeH, and Et3N) with excess CS2 followed by treatment of the resulting dianion [{μ-Se(CH2)3Se-μ}{(μ-S═CS)Fe2(CO)6}2]2– with (diphosphine)NiCl2, 9b–11b were obtained by reactions of the dianion [{μ-Se(CH2)3Se(CH2)3Se-μ}{(μ-CO)Fe2(CO)6}2]2– (formed in situ from Fe3(CO)12, HSe(CH2)3Se(CH2)3SeH, and Et3N) with excess CS2 and subsequent treatment of the resultant [Et3NH]+ salt of the two-μ-CS2-containing dianion [{μ-Se(CH2)3Se(CH2)3Se-μ}{(μ-S═CS)Fe2(CO)6}2]2– with (diphosphine)NiCl2. A possible pathway for production of the two types of novel macrocycles 9a–11a and 9b–11b is suggested. In addition, the structures of all the linear and macrocyclic products were characterized by elemental analysis and spectroscopy and, for some of them, by X-ray crystallography.