Synthesis and Structural Characterisation of Palladium(II) Complexes with N,N',N-Tridentate N'-Substituted N,N-Di(2-picolyI)amines and their Application to Methyl Methacrylate Polymerisation

摘要

The reaction of [Pd(CH3CN)2Cl2] with TV-substituted N,N'-di(2-picolyl)amine-based ancillary ligands, for example N,N-di (2-picolyl)cyclohexylmethylamine (L1), N,N-di(2-picolyl)benzylamine (L2), N,N-di(2-picolyl)aniline (L3), and 1,4-bis [bis(2-pyridylmethyl)aminomethyl]benzene (L4), in the presence of NaClO4 in ethanol yields a new series of [(N N'N) PdCl]X (X = ClO4, Cl) complexes, i.e. mononuclear [L_nPdCl]ClO4 (L_n = L_n, L2, L3) and binuclear [L4Pd2Cl2]Cl2. X-Ray crystallographic analysis determined that the Pd atom in complexes [(AW7V)PdCl]X showed a slightly distorted square-planar geometry involving three nitrogen atoms and a chlorido ligand. Moreover, the unit cell included a ClO^ or Cl~ anion as the counterion. The complex [L1PdCl]ClO4 showed the highest catalytic activity for the polymerisation of methyl methacrylate in the presence of modified methylaluminoxane at 60°C among the mononuclear Pd~(II) complexes. Specifically, the activity of binuclear [L4Pd2Cl2]Cl2 was 2-fold higher than the corresponding mononuclear [L2PdCl] ClO4 per active palladium metal centre.