Directed regioselectivity in cyclometallated palladium(II) compounds of N-benzylidenebenzylamines.: Crystal and molecular structure of [Pd{3,4-(OCH2O)C6H2C(H)=NCH2-[3,4-(OCH2O)C6H3]-C2,N}(μ-O2CMe)]2

The reaction of the Schiff base ligand 3,4-(OCH2O)C6H3C(H)=NCH2[3,4-(OCH2O)C6H3] (a) with Pd(OAc)(2) yields two endocyclic cyclometallated compounds: [Pd{3,4-(OCH2O)C6H2C(H)=NCH2[3,4-(OCH2O)C,H,]-C2,N}(mu -O2CMe)](2) (C2,N-bonded) (1a), and [Pd{3,4-(OCH2O)C6H2C(H)=NCH2[3,4-(OCH2O)C6H3]-C6,N}(mu -O2CMe)](2) (C6,N-bonded) (1b), which may be separated by fractional crystallization. The corresponding cyclopalladated dimers with bridging chloride ligands, 2a, 2b, have been prepared by a metathesis reaction with aqueous sodium chloride. Treatment of the latter compounds with tertiary phosphines in the appropriate molar ratio gave the mono and dinuclear compounds, 3a-8a and 3b-5b, respectively. The structure of compound la has been determined by X-ray diffraction analysis. The molecular configuration is a dimeric form of the anti isomer with the cyclopalladated moieties in an 'open-book' arrangement linked by two acetate bridging ligands. (C) 2001 Elsevier Science Ltd. All rights reserved.