A series of mono-and binuclear Co（Ⅱ） complexes （Col-Co7） supported by quinoline-2-imidate ligands were synthesized and thoroughly characterized. Measured by single crystal X-ray crystallography, complexes Col and...A series of mono-and binuclear Co（Ⅱ） complexes （Col-Co7） supported by quinoline-2-imidate ligands were synthesized and thoroughly characterized. Measured by single crystal X-ray crystallography, complexes Col and Co3 adopted distorted tetrahedral structures around the cobalt center. Upon activation by ethylaluminium sesquichloride （EASC）, these cobalt complexes exhibited high catalytic activity and cis-l,4-selectivity towards 1,3-butadiene polymerization. The effects of ligand environment, polymerization temperature, and cocatalyst types on the polymerization were investigated in detail. Interestingly, the binuclear Co（Ⅱ） complexes exhibited high thermal stability, and the polymer yields were up to 97.2% even at a high temperature of 70 ℃.展开更多
A series of pyrazolylimine ligated Co(II) and Fe(II) complexes with general formula of(PhC=N(C_6H_3(R_1)2-2,6)(C_3 HN_2(R_2)2-3,5)MtCl_2(R_1 = Me, R_2 = H, Mt = Co(1 a), Fe(2 a); R_1 = Me, R_2 = Me, Mt = Co(1b), Fe(2b...A series of pyrazolylimine ligated Co(II) and Fe(II) complexes with general formula of(PhC=N(C_6H_3(R_1)2-2,6)(C_3 HN_2(R_2)2-3,5)MtCl_2(R_1 = Me, R_2 = H, Mt = Co(1 a), Fe(2 a); R_1 = Me, R_2 = Me, Mt = Co(1b), Fe(2b); R_1 = iPr, R_2 = H, Mt = Co(1 c), Fe(2 c); R_1 = i Pr, R_2 = Me, Mt = Co(1 d), Fe(2 d); R_1 = i Pr, R_2 = Ph, Mt = Co(1 e), Fe(2 e)) were synthesized and thoroughly characterized.Determined by single crystal X-ray diffraction, complexes 1 b and 2 b revealed dimeric structures, in which distorted trigonal bipyramid geometries were adopted for each metal centers. In the presence of ethylaluminum sesquichloride(EASC), all the cobalt complexes displayed high activities in 1,3-butadiene polymerization, affording polybutadienes with predominant cis-1,4 contents(up to 97.0%).Influences of ligand structure and polymerization parameters on catalytic performance were investigated systematically. For pyrazolylimine iron(II) dichloride complexes, the catalytic activities and microstructures of the resultant polybutadienes were highly dependent on ligand structures and polymerization conditions. For complex 2 a, changing cocatalyst from trialkyl aluminums to methyl aluminoxane(MAO) led to an shift of selectivity from high cis-1,4-to trans-1,4-/1,2-manner. Being activated by MAO, complexes 2 a and 2 b gave trans-1,4-/1,2-binary polybutadienes, while complexes 2 c, 2 d, and 2 e afforded cis-1,4-enriched polymers.展开更多
基金financially supported by the National Key R&D Program of China (No.2017YFB0307100 (2017YFB0307103))National Basic Research Program of China (No.2015CB654700 (2015CB654702))
文摘A series of mono-and binuclear Co（Ⅱ） complexes （Col-Co7） supported by quinoline-2-imidate ligands were synthesized and thoroughly characterized. Measured by single crystal X-ray crystallography, complexes Col and Co3 adopted distorted tetrahedral structures around the cobalt center. Upon activation by ethylaluminium sesquichloride （EASC）, these cobalt complexes exhibited high catalytic activity and cis-l,4-selectivity towards 1,3-butadiene polymerization. The effects of ligand environment, polymerization temperature, and cocatalyst types on the polymerization were investigated in detail. Interestingly, the binuclear Co（Ⅱ） complexes exhibited high thermal stability, and the polymer yields were up to 97.2% even at a high temperature of 70 ℃.
基金financially supported by the National Basic Research Program of China(No.2015CB654700(2015CB654702))the National Natural Science Foundation of China(No.21801236)
文摘A series of pyrazolylimine ligated Co(II) and Fe(II) complexes with general formula of(PhC=N(C_6H_3(R_1)2-2,6)(C_3 HN_2(R_2)2-3,5)MtCl_2(R_1 = Me, R_2 = H, Mt = Co(1 a), Fe(2 a); R_1 = Me, R_2 = Me, Mt = Co(1b), Fe(2b); R_1 = iPr, R_2 = H, Mt = Co(1 c), Fe(2 c); R_1 = i Pr, R_2 = Me, Mt = Co(1 d), Fe(2 d); R_1 = i Pr, R_2 = Ph, Mt = Co(1 e), Fe(2 e)) were synthesized and thoroughly characterized.Determined by single crystal X-ray diffraction, complexes 1 b and 2 b revealed dimeric structures, in which distorted trigonal bipyramid geometries were adopted for each metal centers. In the presence of ethylaluminum sesquichloride(EASC), all the cobalt complexes displayed high activities in 1,3-butadiene polymerization, affording polybutadienes with predominant cis-1,4 contents(up to 97.0%).Influences of ligand structure and polymerization parameters on catalytic performance were investigated systematically. For pyrazolylimine iron(II) dichloride complexes, the catalytic activities and microstructures of the resultant polybutadienes were highly dependent on ligand structures and polymerization conditions. For complex 2 a, changing cocatalyst from trialkyl aluminums to methyl aluminoxane(MAO) led to an shift of selectivity from high cis-1,4-to trans-1,4-/1,2-manner. Being activated by MAO, complexes 2 a and 2 b gave trans-1,4-/1,2-binary polybutadienes, while complexes 2 c, 2 d, and 2 e afforded cis-1,4-enriched polymers.
