The bimetallic activation of white phosphorus by trans-[RhCl(CO)(dppm)]2 results in a tetrahedro-Rh2P2 moiety

The reaction of trans-[RhCl(CO)(dppm)]2 with P4 carried out at room temperature showed that bimetallic cooperation resulted in the cleavage of P4, giving a mu,eta2-P2 (mu-k2:k2-P2) ligand coordinated to the two metal centres. The new complex cis-[Rh2(CO)2(mu-dppm)2(mu,eta2-P2)] has been fully characterised in solution by NMR spectroscopy and in the solid state by single-crystal X-ray diffraction. The Rh-Rh distance of 2.723(18) Å is consistent with the presence of a metal-metal single bond, which was supported by theoretical analysis showing that the HOMO of the complex has metal-metal bond character. A literature survey revealed that, in most cases, the P2 unit acts as a P24- ligand, and also in the case at hand the diphosphenyl ligand behaves as an eight-electron donor with all the pi* combinations occupied and donates into four empty metal combinations.