SYNTHESIS OF HALOGENO, PSEUDOHALOGENO, AND CARBOXYLATOPALLADIUM(IV) COMPLEXES BY HALOGEN EXCHANGE - CRYSTAL-STRUCTURE OF AZIDO(2,2'-BIPYRIDYL)-BENZYLPALLADIUM(II), FORMED ON REDUCTIVE ELIMINATION OF ETHANE FROM PD(N3)ME2(CH2PH)(BPY)

The first examples of fluoro, pseudohalogeno, and carboxylatopalladium(IV) complexes have been obtained by the exchange of the bromo ligand in PdBrMe2(CH2Ph)(bpy) (bpy = 2,2'-bipyridyl) on addition of a silver salt, or silver nitrate and the appropriate anion, in acetonitrile. The syntheses have permitted a study of the effect of groups X on the selectivity in reductive elimination of ethane and ethylbenzene from PdXMe2(CH2Ph)(bpy). For X = Br, N3, SCN, or O2CPh, reductive elimination from the unstable palladium(IV) complexes in acetone gives ethane and PdX(CH2Ph)(bpy) only, but these products together with ca. 10% of ethylbenzene and PdXMe(bpy) are formed from the complexes PdXMe2(CH2Ph)(bpy) (X = F, Cl, I, OCN, SeCN, O2CCF3). The binding mode of the ambidentate pseudohalides OCN-, SCN- and SeCN- has not been determined.