Neutral and anionic 2-methyl-6-nitrophenyl palladium(II) complexes. The X-ray crystal structure of bis(benzyltriphenylphosphonium)trans-di-µ-chloro-bis[chloro(2-methyl-6-nitrophenyl)palladate(II)]–acetone (1/2)

Abstract

By reacting HgR₂(R = C₆H₃Me-2,NO₂-6) with [PPh₃(CH₂Ph)]₂[Pd₂Cl₄(µ-Cl)₂](2 : 1) in refluxing acetone the complex trans-[PPh₃(CH₂Ph)]₂[Pd₂Cl₂(µ-Cl)₂R₂]·2Me₂CO (1) crystallizes in high yield. The anion is a centrosymmetric dimer with both palladium atoms having square-planar co-ordination. The mutually trans chloro ligpnds, one terminal and the other bridging, have similar Pd–Cl bond lengths [2.322(4) and 2.334(4)Å, respectively], both being shorter than the other Pd–Cl bonds [2.448(4)Å] corresponding to the bridging chloro ligands trans to the phenyl groups. The angles between the phenyl rings and the ‘PdCl₂(µ-Cl)₂’ moiety plane or their own nitro group planes are 73.3 or 140.2°, respectively. The shortest Pd–O distance [2.893(6)Å] is too long to assume intramolecular bonds. This complex is the first aryl palladium derivative of such a stoicheiometry described so far. From its solutions in dimethyl sulphoxide (dmso) the complex [PdCl₂(R)(dmso)]^– can be isolated. Complex (1) also reacts with PPh₃(1 : 4) or bidentate ligands (1 : 2) to form trans-[PdCl(R)(PPh₃)₂] or cis-[PdCl(R)(L–L)](L–L = 2,2′-bipyridine or 1,10-phenanthroline) respectively.