No abstract

The synthesis of Ni(II) and Pd (II) coordination complexes containing Schiff's bases derived from the condensation of 2,4dihydroxybenzaldehyde with 4-chloroaniline (L1) or 3,5-dichloroaniline (L2) is described. The condensation of ligands L1 and L2 with chlorodiisopropylphosphine in the presence of a base produced the corresponding non-symmetric pincer ligands POCOP-1 and POCOP-2 with the unexpected CÀ P bond formation by a hydrophosphorylation of the imine process. The new CÀ P bond formation probably occurring by a Kabachnik-Field mechanism type without the requirement of catalysts or additional reagents. Further treatment of ligands POCOP-1 or POCOP-2 with NiCl 2 afforded the non-symmetric pincer complexes Ni(II)-POCOP-1 and Ni(II)-POCOP-2. The crystal structures of L1, 3, Ni(II)-POCOP-1 and Ni(II)-POCOP-2 were unequivocally determined by single crystal X-ray diffraction studies. In addition, the metal complexes were used as catalysts in Suzuki-Miyaura couplings under microwave irradiation, being the Pd(II) derivatives the best catalysts of the series when compared to their Ni(II) analogues under the same reaction conditions.