Phosphenium Hydride Reduction of [(cod)MX] (M = Pd, Pt; X = Cl, Br): Snapshots on the Way to Phosphenium Metal(0) Halides and Synthesis of Metal Nanoparticles.

The outcome of the reduction of [(cod)PtX] (X = Cl, Br; cod = 1,5-cyclooctadiene) with N-heterocyclic phosphenium hydrides NHP-H depends strongly on the steric demand of the N-aryl group R and the nature of X. Reaction of [(cod)PtCl] with NHP-H featuring bulky N-Dipp groups produced an unprecedented monomeric phosphenium metal(0) halide [(NHP)(NHP-H)PtCl] stabilized by a single phosphine ligand. The phosphenium unit exhibits a pyramidal coordination geometry at the phosphorus atom and may according to DFT calculations be classified as a Z-type ligand.