(Triphenylphosphane)gold(I) scrambling in a hexanuclear complex of phenylene-1,2-bis(phosphane)

Phenylene-1,2-bis(phosphane) reacts with two mole-equivalents of tris[(triphenylphosphane)gold(I)]oxonium tetrafluoroborate in dichloromethane at -78°C to give high yields of a hexanuclear complex (C₆H₄[P(AuPPh₃)₃]₂] ²⁺ · 2 BF₄^- (1). The variable-temperature ³¹P{¹H}-NMR spectra of the product in CD₂Cl₂ at -80°C are compatible with a static structure featuring three Ph₃PAu units associated with each of the two C₆H₄P₂ phosphide functions, as derived from a clear doublet/quartet pattern. At 50°C in CDCl₃, however, there is rapid intramolecular scrambling of these Ph₃PAu units, which gives rise to a triplet/septet pattern with the J(P,P) value reduced to exactly one half of the value at the low-temperature limit.