Carbon(0)-Bridged Pt/Ag Dinuclear and Tetranuclear Complexes Based on a Cyclometalated Pincer Carbodiphosphorane Platform

A carbon(0)-bridged Pt2Ag2 cluster was synthesized from the reaction of a cyclometalated pincer carbodiphosphorane platinum complex with AgOTf, by forming Pt­(II)←C(0)→Ag­(I) dative bonds along with Pt­(II)–Ag­(I) and Ag­(I)–Ag­(I) metal–metal interactions. X-ray diffraction analysis reveals that the cluster adopts an antiparallel sandwich structure with a ladder-shaped PtC/AgAg/CPt core. The coordination plane of the platinum unit is highly distorted due to the in-plane steric repulsion between the PEt3 ligand on the platinum and the nearest proton on each of the two cyclometalated phenyl rings in the pincer carbodiphosphorane framework. The cluster is very labile and displays different reactivity patterns toward trivalent phosphorus ligands. In the reaction with bulky PPh3, a dinuclear complex was formed because of coordination of PPh3 to the silver atom upon cleavage of the tetranuclear core. In contrast, replacement of the PEt3 on the platinum center by P­(OPh)3, which is sterically less demanding, led to a dinuclear complex where the eliminated PEt3 ligand recoordinated to the silver atom.