ORGANOPALLADIUM COMPLEXES WITH PALLADIUM AT THE OXIDATION STAGE-+IV ARE STABILIZED BY TRIPODAL OXYGEN LIGANDS

The first trialkylpalladium(IV) complexes, stabilised exclusively thro ugh oxygen donor ligands, are reported. The dimethyl palladium complex es [PdMe2(tmeda)] and [PdMe2(bpy)] (tmeda = N,N,N',N'-tetramethylethan ediamine, bpy = bipyridyl) react with alkyl halides RX (= methyl iodid e, benzyl bromide, and allyl bromide) in the presence of the sodium an d the silver salts of the tris-chelating oxygen ligands L- (= [CpCo{PR 2(O)}3]-) to give the palladium(IV) complexes LPdMe2R. Crystals of [Cp Co{PR2(O)}3PdMe3] are triclinic, space group P1BAR (Nr. 2) with A = 9. 065(6) angstrom, B = 14.680(2) angstrom, C = 15.161(7) angstrom, alpha = 112.56(2)-degrees, beta = 104.92(4)-degrees, gamma = 95.04(3), Z = 3, and R = 0.051 for 3590 observed reflections with I > 3 sigma(I). Th e palladium-oxygen and the palladium-carbon distances are 2.18 and 2.0 0 angstrom, respectively.