FLUORIDE-INDUCED REDUCTION OF PALLADIUM(II) AND PLATINUM(II) PHOSPHINE COMPLEXES

A novel redox reaction involving fluoride and phosphine complexes of palladium(II) is reported. The scope of this reaction has been investigated using the ligands PPh3, Ph2P(CH2)nPPh2 (n = 1-4), Ph2PCH2C(CH3)2CH2PPh2, Ph2PCH3, and P(CH2CH2CN)3; several solvents including DMSO, pyridine, acetonitrile, and THF; and either n-Bu4NF.3H2O or KF/18-crown-6 as the fluoride source. The reduction products are palladium(0) phosphine complexes for which this reaction offers a convenient synthetic route. P-31 and F-19 NMR spectra permitted identification of the initial oxidation products as difluorophosphoranes (R3PF2), which subsequently hydrolyzed, forming phosphine oxides if a hydrated fluoride source is used. Results implicating a fluoride-induced redox reaction in the thermal decomposition of [(Ph3P)3PdCl]BF4 to yield [Pd3Cl(PPh2)2(PPh3)3] BF4 are also presented. Preliminary results indicate that platinum complexes also undergo this reaction, but nickel complexes yield NiF2. The X-ray parameters for Pd(dppp)2 (dppp = 1,3-bis(diphenyphosphino)propane) are: monoclinic, space group C2/c (No. 15), a = 18.396 (2) angstrom, b = 13.290 (1) angstrom, c = 20.186 (2) angstrom, beta = 109.383 (5)-degrees, and Z = 4.