The complexation of nickel(II) and palladium(II) by heterotridentate ligands with [P,N,O] donor sets

Phosphorus-containing heterotridentate ligands prepared by the condensation of 2-(diphenylphosphino)aniline with 5-chlorosalicylaldehyde (HL1), 5-nitrosalicylaldehyde (HL2), 5-bromosalicylaldehyde (HL3), 5-methoxysalicylaldehyde (HL4) or 3-methoxysalicylaldehyde (HL5) react directly with NiCl2·6H2O or [(cod)PdCl2] to form complexes of general formula [η3(L)M(II)Cl]. These are characterised by spectroscopic, microanalytical and crystallographic methods. The crystal structures of [η3(L3)Ni(II)Cl] (3) and [η3(L2)Pd(II)Cl] (6) confirm tridentate [P,N,O] coordination of the deprotonated ligands to the metal centres, forming both five- and six-membered rings.