Aurophilic Self-Assembly of a Mo₄Au₂ Phosphinidene Complex with an Unprecedented H-Shaped Planar Metal Core

The isomers [Mo2Cp2(μ-κ1:κ1,η6-PR*)(CO)2] (1) and [Mo2Cp(μ-κ1:κ1,η5-PC5H4)(CO)2(η6-HR*)] (2) (Cp = η5-C5H5; R* = 2,4,6-C6H2tBu3) react with [AuCl(THT)] and with the cation [Au(THT)2]+ (THT = tetrahydrothiophene) to give phosphinidene-bridged Mo2Au complexes resulting from the addition of an AuCl or Au(THT)+ electrophile to their multiple P−Mo bonds. Removal of the Cl− or THT ligand from these derivatives causes a dimerization of the trinuclear structures to give the cationic derivative [{AuMo2Cp(μ3-κ1:κ1:κ1,η5-PC5H4)(CO)2(η6-HR*)}2]2+, which displays a novel H-shaped metal core held by strong Mo−Au dative bonds [2.768(1) Å] and an aurophilic interaction [Au−Au = 3.022(1) Å].