A Traditional Synthetic Method, and a New Structural Motif, for Molybdenum−Gold Clusters:  Synthesis and Solid-State Structure of Au₈{Mo(CO)₅}₄(PPh₃)₄

The neutral cluster [Au₈Mo₄(CO)₂₀(PPh₃)₄] was synthesized in low yield from [AuCl(PPh₃)] and [Mo₂(CO)₁₀]^2- in acetonitrile at room temperature. The cluster was characterized by X-ray analysis, IR, and ³¹P NMR spectroscopy. Its solid-state structure consists of four Au₃Mo tetrahedral units, fused by four Au atoms in a ring. The average bond lengths are Au−Au 2.77 Å and Mo−Au 2.93 Å. The internal angles of the planar square ring are very close to 90°.