Three kinds of bimetallic Schiff base titanium complexes with different substituent moieties on organic ligands were synthesized.Ring-opening polymerizations （ROP） of lactides were carried out by using these titaniu...Three kinds of bimetallic Schiff base titanium complexes with different substituent moieties on organic ligands were synthesized.Ring-opening polymerizations （ROP） of lactides were carried out by using these titanium complexes as catalysts.The polymerization data and kinetic studies showed that complex 1a had the highest activity and complex 2a had the lowest activity for ROP of lactides.Moreover,all these three newly synthesized bimetallic titanium complexes showed higher polymerization activity and better molecular weight control than their monometallic counterparts reported in our previous work.展开更多
From the self-assembly of the typical Salen-type Schiff-base ligand H2L and Zn（OAc）2.2H20 in the molar ratio of 1：1 or 1：2, the mononuclear [Zn（L）（H2O）] （1） or binuclear [Zn2（L）（OAc）2（H2O）] （2） are o...From the self-assembly of the typical Salen-type Schiff-base ligand H2L and Zn（OAc）2.2H20 in the molar ratio of 1：1 or 1：2, the mononuclear [Zn（L）（H2O）] （1） or binuclear [Zn2（L）（OAc）2（H2O）] （2） are obtained, respectively. For both complexes 1 and 2, the unsaturated five-coordinate coordination environment to the catalytic active centers （Zn2＋ ions） permits the monomer insertion for the effective solution copolymerization of cyclohexene oxide and maleic anhydride. All the solution copolymerizations afford poly（ester-co-ether）s, while lower catalyst and co-catalyst concentrations are helpful for the formation of alternating polyester. Of the three co-catalysts, 4-（dimethylamino）pyridine is found to be the most efficient, while an excess thereof is detrimental for chain growth of the copolymers.展开更多
A nickel(Ⅱ) cluster,{[Ni(L)H2O]2(OAc)2Ni}.2EtOH,has been synthesized by the means of the complexation of nickel(Ⅱ) acetate tetrahydrate with a new Salen-type bisoxime ligand (H2L,4,4'-dimethoxy-2,2'-[ethylen...A nickel(Ⅱ) cluster,{[Ni(L)H2O]2(OAc)2Ni}.2EtOH,has been synthesized by the means of the complexation of nickel(Ⅱ) acetate tetrahydrate with a new Salen-type bisoxime ligand (H2L,4,4'-dimethoxy-2,2'-[ethylenedioxybis (nitrilo-methylidyne)]diphenol). The crystal structure shows that the hexacoodinated terminal nickel(Ⅱ) ions lie in the N2O2 coordination sphere of Salen-type bisoxime ligands,quadruple μ-phenoxo oxygen atoms from two [NiL] chelates coordinated to the central nickel(Ⅱ) ion,and the two acetate anions coordinated to three nickel(Ⅱ) ions through Ni-O-C-O-Ni bridges. Thus,all the three nickel atoms of the cluster have distorted octahedral geometries. CCDC:736762.展开更多
文摘Three kinds of bimetallic Schiff base titanium complexes with different substituent moieties on organic ligands were synthesized.Ring-opening polymerizations （ROP） of lactides were carried out by using these titanium complexes as catalysts.The polymerization data and kinetic studies showed that complex 1a had the highest activity and complex 2a had the lowest activity for ROP of lactides.Moreover,all these three newly synthesized bimetallic titanium complexes showed higher polymerization activity and better molecular weight control than their monometallic counterparts reported in our previous work.
基金financially supported by the National Natural Science Foundation of China(Nos.91222201,21173165 and 20871098)the Program for New Century Excellent Talents in Universities from the Ministry of Education of China(No.NCET-10-0936)+4 种基金the State Key Laboratory of Structure Chemistry(20100014)the Provincial Natural Foundation(2011JQ2011) of Shaanxithe Education Committee Foundation of Shaanxi Province(11JK0588,12JK0577)Graduate Innovation and Creativity Fund(YZZ12038) of Northwest UniversityHong Kong Research Grants Council(HKBU 202407 and FRG/06-07/II-16)
文摘From the self-assembly of the typical Salen-type Schiff-base ligand H2L and Zn（OAc）2.2H20 in the molar ratio of 1：1 or 1：2, the mononuclear [Zn（L）（H2O）] （1） or binuclear [Zn2（L）（OAc）2（H2O）] （2） are obtained, respectively. For both complexes 1 and 2, the unsaturated five-coordinate coordination environment to the catalytic active centers （Zn2＋ ions） permits the monomer insertion for the effective solution copolymerization of cyclohexene oxide and maleic anhydride. All the solution copolymerizations afford poly（ester-co-ether）s, while lower catalyst and co-catalyst concentrations are helpful for the formation of alternating polyester. Of the three co-catalysts, 4-（dimethylamino）pyridine is found to be the most efficient, while an excess thereof is detrimental for chain growth of the copolymers.
文摘A nickel(Ⅱ) cluster,{[Ni(L)H2O]2(OAc)2Ni}.2EtOH,has been synthesized by the means of the complexation of nickel(Ⅱ) acetate tetrahydrate with a new Salen-type bisoxime ligand (H2L,4,4'-dimethoxy-2,2'-[ethylenedioxybis (nitrilo-methylidyne)]diphenol). The crystal structure shows that the hexacoodinated terminal nickel(Ⅱ) ions lie in the N2O2 coordination sphere of Salen-type bisoxime ligands,quadruple μ-phenoxo oxygen atoms from two [NiL] chelates coordinated to the central nickel(Ⅱ) ion,and the two acetate anions coordinated to three nickel(Ⅱ) ions through Ni-O-C-O-Ni bridges. Thus,all the three nickel atoms of the cluster have distorted octahedral geometries. CCDC:736762.
基金Supported by the National Natural Science Foundation of China(5110208121072049)+1 种基金the University’s Science and Technology Innovation Team of Heilongjiang Province(2010td03)the Science and Technology Bureau of Heilongjiang Province(B201215)
