Influence of phenyl ring substituents in the cyclometallation of Schiff base ligands:: crystal and molecular structures of [Pd-{3,4-(OCH2O)C6H2C(H)=N(Cy)-C2,N}(μ-O2CMe)]2 and [Pd-{3,4-(OCH2CH2O)C6H2C(H)=N(Cy)-C6,N}(μ-O2CMe)]2

Reaction of Pd(OAc)(2) with the Schiff base ligands 3,4-{O(CH2)(n)O}C6H3C(H)=NR (n = 1, 2; R = Cy, 3,4-(OCH2O)C6H3CH2-) leads to dinuclear cyclometallated products in which each palladium atom is C,N bonded to a deprotonated organic ligand, and to two acetate groups which bridge both metal centers. Treatment of 3,4-{O(CH2)(2)O}C6H3C(H)=NCH2CH2NMe2 with [PtMe2(COD)] gives mononuclear compounds with the ligand as terdentate through the [C, N, N] atoms. The regioselectivity of the cyclometallation processes is discussed by H-1-NMR spectroscopy and X-ray diffraction studies. (C) 2000 Elsevier Science S.A. All rights reserved.