RESUMO
The heterobinuclear complex OsCl2(PPh3)2[CHC(PPh3)CFcO] (Fc = (C5H4)Fe(C5H5)) (1) in which the two metal centers were connected by the skeleton of the osmafuran and cyclopentadienyl was synthesized via a one-pot reaction of OsCl2(PPh3)3 and FcCOC[triple bond, length as m-dash]CH in high yield. Three derivatives (Os(η2-OCOO)(PPh3)2[CHC(PPh3)CFcO] (2), Os(NCS)2(PPh3)2[CHC(PPh3)CFcO] (3), and OsCl2(dppb)[CHC(PPh3)CFcO] (dppb = Ph2P(CH2)4PPh2) (4)) were obtained by the ligand substitution reactions of complex 1 with different reagents (Cs2CO3 (2), NaSCN (3) and dppb (4)), respectively. All of these complexes were characterized by NMR spectroscopy and elemental analysis and the structures of complexes 1, 3 and 4 were further confirmed by single crystal X-ray diffraction. Their electrochemical properties were studied by cyclic voltammetry and square wave voltammetry. The first redox wave was ascribed to the couple Os(ii)/Os(iii). All of these complexes exhibit two redox processes with a large peak separation. However, UV-Vis-NIR combined with theoretical calculation clearly indicated that (1) the Os center plays a major role in the one-electron oxidation process of heterobinuclear complexes 1-4 and the osmafuran could be better described as a carbene ligand; (2) the electronic communication between the Os and Fe center is absent, and the osmafuran with the electron-withdrawing phosphonium substituent actually functioned as an insulating bridge.
