Cycloneophylpalladium(IV) Complexes: Formation by Oxidative Addition and Selectivity of Their Reductive Elimination Reactions

The cycloneophylpalladium(II) complexes [Pd-(CH2CMe2C6H4)(kappa(2)-N,N'-L)] (L = RO(CH2)(3)N(CH2-2-C5H4N)(2), R = H, Me) undergo oxidation to Pd(IV) with bromine or iodine to give [PdX(CH2CMe2C6H4)(kappa(3)-N,N',N ''-L)PC (X = Br, I) or with methyl iodide to give the transient complexes [PdMe(CH2CMe2C6H4)(kappa(3)-N,N',N ''-L)]I. The products of Br2 and Br, I), are sufficiently stable to be isolated, but they decompose slowly in solution by reductive elimination to give the palladium- (II) products [PdX(kappa(3)-N,N',N ''-L)]X (X = Br, I). The organic products are formed via either CH2-Ar or CH2-X bond formation. In the latter case, neophyl rearrangement and protonolysis steps follow reductive elimination to give a mixture of organic products. The methylpalladium(IV) complexes [PdMe(CH2CMe2C6H4)(kappa(3)-N,N',N ''-L)]I decompose at 0 degrees C by selective reductive elimination with Me-Ar bond coupling to give the alkylpalladium(II) complex [Pd(CH2CMe2-2-C6H4Me)(kappa(3)-N,N',N ''-L)]I. The mechanisms of the reactions have been explored by kinetic studies.