Directed regioselectivity in cyclometallated palladium(II) compounds of N-benzylidenebenzylamines. Crystal and molecular structure of [Pd{3,4-(OCH 2O)C 6H 2C(H)NCH 2[3,4-(OCH 2O)C 6H 3]- C2, N}(μ-O 2CMe)] 2

Abstract

The reaction of the Schiff base ligand 3,4-(OCH 2O)C 6H 3C(H)NCH 2[3,4-(OCH 2O)C 6H 3] ( a) with Pd(OAc) 2 yields two endocyclic cyclometallated compounds: [Pd{3,4-(OCH 2O)C 6H 2C(H)NCH 2[3,4-(OCH 2O)C 6H 3]- C2, N}(μ-O 2CMe)] 2 ( C2, N-bonded) ( 1a), and [Pd{3,4-(OCH 2O)C 6H 2C(H)NCH 2[3,4-(OCH 2O)C 6H 3]- C6, N}(μ-O 2CMe)] 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 1a 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.