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

Oxidative addition of organo halides, RX, to dimethylpalladium(II) complexes, PdMe2(tripod), has led to isolation of the first examples of ethyl-, n-propyl-, (η1-benzyl)-, and (η1-ally)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-PdRMe2{(py)-(mim)2CH-N,Nʹ,Nʺ}]X. Tris(pyrazol-1-yl)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(η3-C3H5)]2 and the complex salt [Pd(η3-C3H5){(pz)3CH}]-[PdBr2(η3-C3H5)]. Allyl exchange occurs for [Pd(η3-C3H5)(L)][PdBr2(η3-C3H5)] (L = (pz)3CH, (pz)2CMe2), with (pz)3CH also exchanging coordinated and uncoordinated pz groups and with the cation [Pd(η3-C3H5){(pz)2CMe2}]+ present as two conformers in equilibrium. © 1990, American Chemical Society. All rights reserved.