Syntheses, characterization and X-ray structure of palladium(II) and nickel(II) complexes of tetradentate pyrrole containing ligands

Palladium(II) and nickel(II) complexes with tetradentate ligands derived from pyrrole 2-carboxaldehyde and various diamines have been synthesized and characterized. The complexes are neutral and the coordination around the metal is square-planar; they are able to activate the molecular hydrogen and to catalyse the homogenous hydrogenation of phenylacetylene. The X-ray structures of N,N′-cycloexylenebis(pyrrol-2-ylmethyleneamine) (H2L4), PdL4 and PdL3 (H2L3, N,N′-propylenebis(pyrrol-2-ylmethyleneamine)) are discussed.