Syntheses,Crystal Structures and Catalytic Performance of 2,6-Bis(imino) pyridyl Manganese Complexes

Reactions of equalmolar ratios of MnCl2 4H2O and the tridentate ligands 2,6-bis[1-(2,6-dimethylphenylimino)ethyl]pyridine(L1),2,6-bis[1-(2,6-diethy phenylimino)ethyl]pyridine(L2),and 2,6-bis[1-(2,6-dimethylphenylimino)ethyl]pyridine(L3) in acetonitrile afforded the five-coordinated complexes L1Mn(Ⅱ)Cl2 CH3CN(1),L2Mn(Ⅱ)Cl2 CH3CN(2) and L3Mn(Ⅱ)Cl2 CH3CN(3),respectively.The three complexes were characterized using elemental analysis,IR spectroscopy and single-crystal X-ray diffraction.Crystallographic studies on complexes 1—3 reveal the pentacoordinate with geometries that can be best described as distorted trigonal bipyramidal.Complex 1 crystallizes in the monoclinic system,space group P21/n,with a=1.3304(3) nm,b=1.4864(3) nm,c=1.4423(3) nm;β=108.41(3)°,V=2.7063(9) nm3,Z=4,F(000)=1116,R1= 0.0465;complex 2 belongs to monoclinic system with space group P21/c,with a=1.2919(1) nm,b=1.5283(1) nm,c=1.6362(1) nm;β=99.27(1)°,V=3.1883(3) nm3,Z=4,F(000)=1244,R1= 0.0599;complex 3 belongs to monoclinic system with space group P21/n,with a=1.4542(3) nm,b=1.5083(3) nm,c=1.4646(3) nm;β=112.56(3)°,V=2.9667(10) nm3,Z=4,F(000)=1180,R1= 0.0627.Complexes 1—3 exhibit lower catalytic activities for ethylene polymerization after activation with cocatalysts of ～[B(C6F5)4]-.