New mixed metal cluster complexes containing platinum.: The synthesis and structural characterizations of PtFe4(CO)12(COD)(μ5-C) and PtFe4(CO)12(PMe2Ph)2(μ5-C)

The new mixed metal carbide containing cluster compounds PtFe4(CO)(12) (COD)(mu (5)-C) 1 and PtFe4(CO)(12)(PMe2Ph)(2)(mu (5)-C), 2 were obtained by metal-metal exchange reactions between [Et4N](2)[ Fe-5(C)(CO)(14)] with Pt(COD)Cl-2 in the presence of TIPF6 and Pt(PMe2Ph)(2)Cl-2, respectively. Compound 1 was also obtained by the reaction of Fe-5(CO)(15)(mu (5)-C) with Pt(COD)(2) in the presence of UV irradiation but in a lower yield. Both compounds were characterized by a combination of IR, H-1 NMR and single crystal x-ray diffraction analyses. Both complexes consists of a square pyramidal cluster of five metal atoms with an interstitial carbido ligand in the center of the square base. The phosphine ligands in 2 undergo a dynamical intramolecular interchange at a rate that is fast on the H-1 NMR time scale at 45 degreesC, DeltaG(dagger) (at 318 K) = 15.1 kcal/mol.