Highly Reduced Organometallics. 5. Synthesis, Properties, and the Molecular Structure of (Ph3PAu)3V(CO)5, A Gold-Vanadium Cluster

The unusual metal cluster tris((triphenylphosphine)gold)pentacarbonylvanadium, (Ph3PAu)3V(CO)5 (1), has been synthesized by treatment of sodium or cesium salts of the pentacarbonylvanadate(3-) ion, V(CO)53”, with chloro(triphenylphosphine) gold in liquid ammonia (10-15% yields) or in tetrahydrofuran (50-60% yields). An X-ray crystallographic structure determination of this substance shows that 1 is the first neutral derivative of the unknown tetrahedral cluster (Ph3PAu)4 as well as the only established mixed-metal cluster containing vanadium. In 1 eight-coordinate vanadium is bound to a novel tridentate tris(triphenylphosphine)trigold ligand containing gold-gold bonds. All four metal atoms form a slightly distorted tetrahedral cluster. The V(CO)5 group in 1 is best described as being a pseudooctahedral fragment which is bound to a large trigold unit. Infrared spectra of 1 support this view as they resemble those of the octahedral anions V(CO)5L-, where L = PR3, CNR, etc. Chemical reactivity studies demonstrate that 1 is a remarkably robust gold-vanadium carbonyl complex. Triphenylphosphine, soluble halide, and acetonitrile which normally cause facile heterolytic cleavage of gold-vanadium bonds at room temperature are found to have no effect on 1. Crystal data: space group P1, a = 12.840 (6) Å, b = 19.088 (6) Å, c = 12.380 (4) Å, α = 93.82 (3)°, β = 117.26 (3)°, γ = 92.02 (3)°, Z = 2,V = 2684 (4) Å3, and p(calcd) = 1.941 g/cm3.