Stable alkynyl palladium(II) and nickel(II) complexes with terdentate PNO and PNN hydrazone ligands

Chloro and acetato complexes of palladium(II) and nickel(II) with terdentate PNO acylhydrazonic ligands derived from 2-(diphenylphosphino)benzaldehyde have been synthesized and characterized. The acetato complexes are able to activate the CH bond of terminal alkynes, giving stable alkynyl complexes, one of which has been X-ray characterized. The coordination chemistry of the new PNN ligand 2-(diphenylphosphino)benzaldehyde 2-pyridylhydrazone (HL6) has been also investigated and the X-ray crystal structure of the complex [Pd(HL6)Cl][PdL6Cl]Cl·2H2O is reported. Starting from the nickel(II) acetato complex of HL6, it has been possible to obtain a new stable alkynyl derivative.