Germa- and Stanna-closo-dodecaborate in Reaction with [PdCl2(Xantphos)]: P-C and B-H Bond Activation

The two nucleophilic heteroborates germa-closo-dodecaborate and stanna-closo-dodecaborate show different reactivity toward the electrophile [PdCl2(Xantphos)]: In the case of the germanium ligand we found straightforward substitution of one chloride ligand and formation of a Ge-Pd bond. The tin ligand also reacts to give the substitution products [PdCl(SnB11H11)(Xantphos)](-) and [Pd(SnB11H11)(Xantphos)], but the complexes exhibit a subsequent reaction under activation of a B-H and P-C bond. A dinuclear Pd(I)-Pd(I) complex featuring a P-B bond was characterized, and during its formation the evolution of benzene was detected. The respective germanium derivative does not show an activation reaction even at elevated temperature.