Further studies on dppm-stabilized mixed-metal clusters: X-ray structure of PdPtCoCl(CO)3(μ-dppm)2 1

Abstract

The metalloligated mixed-metal cluster [PdPtCo2(CO)7(μ-dppm)2] (2) (dppm = μ-Ph2PCH2PPh2) possesses numerous potential reaction centers (e.g., metal(s), metal-metal bonds, CO, and dppm ligands) and this has previously led to an investigation of the site selectivity of reactions with nucleophiles. The exocyclic CO(CO)4 fragment was substituted with a chloride ligand and the resulting chiral, triangular cluster PdPtCoCl(CO)3(μ-dppm)2 (4) has been structurally characterized. The Pd-Co and Pt-Co edges of this almost equilateral triangle are bridged by a dppm ligand, and two of the three carbonyls borne by the Co atom are semi-triply bridging above and below the plane of the metals. The “Co(CO)3P” fragment behaves as an anionic 4-electron donor organometallic bridging group toward thed9-d9 Pd(I)-Pt(I) unit. Crystal data for4, monoclinic space groupP21/n with Z=4 in a unit cell of dimensionsa=12.291(3),b=19.321(4),c=23.680(5) A,β=100.05(2)°. The structure has been solved from diffractometer data by Patterson, Fourier methods and refined by full-matrix least squares on the basis of 3512 observed reflections (l>3σ) toR(F) andRw(F) values of 0.059 and 0.061.