Benzenedicarbonyl and benzenetricarbonyl linker pyrazolyl complexes of palladium(II):synthesis,X-ray structures and evaluation as ethylene polymerisation catalysts

摘要

A series of novel compounds with pyrazolyl rings(pz)linked by benzenedicarbonyl(L1-L4)and benzenelricarbonyl(L5,L6)have been prepared and structurally characterized.The mutual orientation of their rings was studied by molecular mechanics.These polydentate-species react with PdCl_2(NCMe)_2 to yield dinuclear complexes in which the Pd centers coordinate to one or two pz units,a terminal chloride and two bridging chloride ligands.In complex [{(3,5-~tBu_2pzCO)_3-l ,3,5-C_6H_4}Pd_2Cl_2(mu-Cl)_2]_4 the pyrazolyl ligand L5 acts as a bidentate donor despite the presence of the third pz group.These Pd complexes,when activated with methylaluminoxidc(MAO),exhibit activity in ethylene polymerization.