Synthesis and characterization of nickel and palladium complexes containing hetero-multidentate PNO ligands

Formation of mono- and dinuclear complexes containing ligands stemmed from the condensation of 2,6-diformyl-4-methylphenol derivatives with 2-(diphenylphosphino)aniline (P∼N) was investigated. Condensation of P∼N with 2,6-diformyl-4-methylanisole yielded the desired bis(imine-phosphine) L3, but provided the cyclized benzoazaphospholium compound with 2,6-diformyl-4-methylphenol. Complexation of L3 with (COD)PdCl2 gave the dinuclear complex 4. On the other hand, L3 underwent the intramolecular cyclization in the presence of (DME)NiCl2 via the formation of benzoazaphospholium rings. Template condensation of 2,6-diformyl-4-methylphenol with P∼N in the presence of metal ions yielded the mononuclear nickel(II) and palladium(II) complexes, respectively.