Synthesis of bimetallic Fe-Ni carbonyl clusters: crystal structure of [N(CH3)3CH2Ph][Fe3Ni(CO)8(\uf06d-CO)4(\uf06d-3-H)].

Redox condensation of [Fe3(CO)11]2- with Ni(CO)4 in tetrahydrofuran affords the tetranuclear dianion [Fe3Ni(CO)12]2-. Subsequent protonation with acids results in formation of the corresponding [Fe3Ni(CO)12H]- anion. This monoanionic species has also been obtained by reaction of [Fe3(CO)11]2- with NiCl2\ub7xEtOH. Both Fe3Ni systems have been isolated in the solid state in high yield with a variety of tetrasubstituted ammonium and phosphonium salts. An X-ray diffraction study of the trimethylbenzylammonium salt of [Fe3Ni(CO)12H]- reveals a structure with a tetrahedron of metal atoms surrounded by eight terminal and four edge-bridging carbonyl groups. The hydride ligand has been located over the center of an Fe2Ni face at a distance of 0.60 (3) \uc5 from the trimetal plane. The corresponding [Fe3Ni(CO)12]2- dianion is suggested to posses an analogous structure on the basis of its IR spectrum. Crystallographic data for [C10H16N]+[C12HFe 3NiO12]-: fw 713.64, triclinic, space group P1, Z = 2, a = 7.416 (1) \uc5, b = 13.849 (2) \uc5, c = 14.108 (2) \uc5, \u3b1 = 103.13 (2)\ub0, \u3b2 = 103.15 (2)\ub0, \u3b3 = 99.23 (2)\ub0, R(F2) = 0.030 for 3860 reflections measured at room temperature