The Coordination Chemistry of Pentafluorophenylphosphino Pincer Ligands to Platinum and Palladium

The synthesis of electron-poor PCP pincer ligands 1,3-((C6F5)(2)PO)(2)C6H4, 1,3-((C6F5)(2)PCH2)(2)C6H4, and 1-((C6F5)(2)PO)-3-(tBu(2)PCH(2))C6H4, and their coordination chemistry to platinum and palladium is described. The most electron-poor ligand 1,3-((C6F5)(2)PO)(2)C6H4 (POCOPH) reacts with Group10 metal chloride precursors to form a range of unusual cis, trans-dimers of the type (2)-P,P-[(POCOPH)MCl(L)](2) (M=Pt, Pd; L=Cl, Me), which undergo metallation to form [(POCOP)MCl] pincer complexes only under prolonged thermolysis. The formation of such cis,trans-dimers during pincer complex formation can be mitigated through the use of starting materials with more strongly binding ancillary ligands, improving the overall rate of ligand metallation. Carbonyl complexes of the type [(PCP)M(CO)](+) were synthesised from the pincer chloride complexes by halide abstraction, and displayed large (CO) values, from 2170-2111cm(-1), confirming the electron-poor nature of the compounds. The [(PCP)Pd(CO)](+) complexes also demonstrated the ability to reversibly bind carbon monoxide both in solution and the solid state, with the rate of decarbonylation increasing with increasing wavenumber for the CO stretch.