Mixed Gold(I)−Gold(III) Complexes with Bridging Selenido Ligands. Theoretical Studies of the Gold(I)−Gold(III) Interactions

The gold(I) compounds [Se(AuPPh3)2] and [Se{Au2(μ-dppf)}] (dppf = 1,1‘-bis(diphenylphosphino)ferrocene) react with 1 and 2 equiv of [Au(C6F5)3OEt2] to give the mixed gold(I)−gold(III) derivatives [Se(AuPPh3)2{Au(C6F5)3}n] and [Se{Au2(μ-dppf)}{Au(C6F5)3}n] (n = 1, 2). The
reaction of [Se(AuPPh3)2] with [Au(C6F5)2Cl]2 affords the complex [{Se(AuPPh3)}2{μ-Au(C6F5)2}2]. The crystal structures of [Se{Au2(μ-dppf)}{Au(C6F5)3}] and [{Se(AuPPh3)}2{μ-Au(C6F5)2}2] have been characterized by X-ray diffraction studies. They show dissimilar Au(I)···Au(III) distances, indicating the presence of weak interactions. Quasi-relativistic
pseudopotential calculations on [Se(AuPH3)2(AuR3)], [Se(AuPH3)(AuR3)2]- (R = −H, −CH3),
and [{Se(AuPH3)}2{Au(CH3)2}2] models have been performed at Hartree−Fock and second-order Møller−Plesset perturbation theory levels. There is a good agreement between
experimental and theoretical geometries at the MP2 level.