Phenyl-functionalized diiron diselenolato complexes with intra- or inter-molecular bridging bidentate phosphine ligands

Treatment of 2-phenyl-1,3-bis(selenocyanate)propane with Fe-3(CO)(12) yielded the expected diiron diselenolato complex [(mu-SeCH2)(2)CHC6H5]Fe-2(CO)(6) (1). Reaction of complex 1 with bis(diphenylphosphine)methane (dppm) in refluxing xylene gave an intra-molecular phosphine bridging complex [(mu-SeCH2)(2)CHC6H5]Fe-2(CO)(4)(mu-dppm) (2), while reaction of complex 1 with 1,1'-bis(diphenylphosphino)ferrocene (dppf) in the presence of the decarbonylating agent Me3NO afforded an inter-molecular phosphine bridging tetrairon complex {[(mu-SeCH2)(2)CHC6H5]Fe-2(CO)(5)}(2)(mu, kappa (1), kappa (1)-dppf) (3). All three complexes were characterized by physical-chemical and spectroscopic methods and for complexes 2 and 3 by X-ray crystallography. Their electrochemical behaviors, especially in the presence of HBF4 for 2, were investigated by cyclic voltammetry.