吡啶二亚胺Ni(Ⅱ)配合物的合成、晶体结构及其催化乙烯聚合的研究

由三齿配体2,6-二1-(2-甲基苯基亚胺)乙基]吡啶(L1)和2,6-二(1-苯基亚胺)乙基]吡啶(L2)分别与NiCl2.6H2O在乙腈中反应,合成了两个吡啶二亚胺基氯化镍配合物L1Ni(Ⅱ)Cl2.CH3CN(1)和L2Ni(Ⅱ)Cl2(2).通过元素分析、IR和1HNMR对配体和配合物进行了结构表征,并测定了配合物1和2的晶体结构.X射线衍射分析结果表明,两个配合物均为五配位扭曲三角双锥构型,属单斜晶系,Cc空间群.配合物1的晶胞参数a=2.5783(5)nm,b=1.4843(3)nm,c=1.5866(3)nm;β=122.82(3),°V=5.1024(18)nm3,Z=4,R1=0.0708,配合物2的晶胞参数a=1.5772(1)nm,b=0.8594(1)nm,c=1.5459(1)nm;β=103.27(1),°V=2.039(2)nm3,Z=4,R1=0.0375.配合物1和2经MAO活化后对乙烯聚合表现出较低的催化活性.

Synthesis, Characterization, Crystal Structures of Bis(imino)pyridyl Nickel Complexes and Their Catalytic Performance for Ethylene Polymerization

Reactions of equimolar ratios of NiCl2·6H2O to the tridentate ligands 2,6-bis1-(2-methyl-phenylimino)ethyl]pyridine(L1) or 2,6-bis(1-phenylimino)ethyl]pyridine(L2) in acetonitrile afford the five-coordinated complexes NiCl2L1·CH3CN(1) and NiCl2L2·CH3CN](2), respectively. All ligands and complexes were characterized by using elemental analysis, IR and 1H NMR spectroscopy. The structures of complexes 1 and 2 were determined by single-crystal X-ray diffraction. Crystallographic studies on complexes 1 and 2 reveal both complexes to be pentacoordinated with geometries that can be best described as distorted trigonal bipyramidal. Complex 1 crystallizes in the monoclinic system, space group Cc, with a=2.578 3(5) nm, b=1.484 3(3) nm, c=1.586 6(3) nm; β=122.82(3)°, V=5.102 4(18) nm3, Z=4, R1=0.070 8. Complex 2 belongs to monoclinic system with space group Cc, a=1.577 2(1) nm, b=0.859 4(1) nm, c=1.545 9(1) nm; β=103.27(1)°, (V=2.039 4(2) nm3,) Z=4, R1=0.037 5. Complexes 1 and 2 exhibit lower catalytic activities for ethylene polymerization upon activation with MAO.