Synthesis of the Stable Organopalladium(IV) Complexes [fac-PdRMe2(tripod)]X and Selective Reductive Elimination of Ethane from (eta-1-Allyl)palladium(IV) Complexes To Form (eta-3-Allyl)palladium(II) Complexes

Abstract

Oxidative addition of organo halides, RX, to dimethylpalladium(II) complexes, PdMe2(tripod), has led to isolation of the first examples of ethyl-, n-propyl-, (eta-1-benzyl)-, and (eta-1-allyl)palladium(IV) complexes. With the tripod ligand as bis(1-methylimidazol-2-yl)(pyridin-2-yl)methane,(py)(mim)2CH, the palladium(IV) complexes occur as mixtures of isomers with R trans to py and mim groups in [fac-PdRMe,{(py)(mim)2CH-N,N',N'}]X. Tris(pyrazo1-1-y1)methane as a ligand gives unstable palladium(IV) complexes, with the benzyl and 2-propenyl complexes undergoing facile reductive elimination of ethane to form organopalladium(II) products, including [PdI(eta-3-C3H5)]2, and the complex salt [Pd(eta-3-C3H5){(pz)3CH]]- [PdBr2(eta-3-C3H5)]. Allyl exchange occurs for [Pd(ete-3-C3H5)(L)][PdBr2(eta-3-C3H5)] (L = (pz)3CH, (pz)2CMe2), with (pz)3CH also exchanging coordinated and uncoordinated pz groups and with the cation [Pd(eta-3-C3H5){(pz)2CMe2}]+ present as two conformers in equilibrium.