SYNTHESIS AND STRUCTURAL STUDIES OF PHENYL(IODO)PALLADIUM(II) AND METHYL(PHENYL)PALLADIUM(II) COMPLEXES OF BIDENTATE NITROGEN DONOR LIGANDS

Phenylpalladium(II) complexes of the type PdIPh(NN), with NN = N,N,N′,N′-tetramethylethylenediamine (tmeda) or 2,2′-bipyridyl (bpy), can be conveniently prepared in 70-95% yield by oxidative addition of iodobenzene to bis(dibenzylideneacetone)palladium(O) in the presence of the appropriate nitrogen donor ligand. The bromo analogues were obtained in only 5-12% yield in this way. The complex PdIPh(tmeda) (1a) reacts readily with MeLi to give PdMePh(tmeda) (3) in 88% yield, whereas PdIPh(bpy) (2a) gives PdMePh(bpy) (4) and PdMe2(bpy) in varying ratios. The formation of PdMe2(bpy) was found to result from the synergistic action of lithium iodide and methyllithium. Pure PdMePh(bpy) (4) was obtained in 82% yield via ligand-exchange from PdMePh (tmeda) (3). The crystal structures of PdIPh(NN) (1a, 2a) and PdMePh(NN) (3, 4) complexes were determined by X-ray diffraction studies. The results show that the phenyl group is alw ays oriented perpendicular to the coordi 3 (14.3(2)°). The PdN bond distances in the tmeda complexes (2.127(6)-2.210(3) Å) are larger than those in the bpy-coordinated complexes (2.070(8)-2.144(8) Å). Similarly, the PdC(Me) bond distances (2.5703(8) and 2.575(1) Å) are larger than the PdC(Pb) bond distances (1.985(3)-1.996(10)Å). © 1994.