Synthesis, solid-state structure, and electronic nature of a phosphinine-stabilized triangulo palladium cluster

The reaction of Pd(OAc)(2) with an excess of 2,4,6-triphenylphosphinine res ults in the formation of a red dimeric Pd-0 complex of unknown structure. T reatment of this complex with PEt3 affords a novel green triangulo Pd, clus ter that is stabilized by three phosphinine and three PEt3 ligands. An X-ra y structural analysis shows that the phosphinine ligands serve as bridges b etween two Pd atoms. Quantum-mechanical calculations of a model compound re produce the experimental geometry of the real complex adequately and also i lluminate the bonding properties. Specifically, the interaction energy betw een each phosphinine ligand and the Pd-3 core amounts to 42.2 kcal mol(-1) and involves both sigma and pi orbitals.