CATALYTIC COPOLYMERIZATION OF STYRENE AND ETHYLENE BY NEUTRAL NICKEL(Ⅱ) COMPLEXES IN EMULSION

Emulsion copolymerization of styrene and ethylene catalyzed by a series of neutral nickel(Ⅱ) complexes was carried out in an aqueous system to give high-molecular-weight copolymers.The copolymers and emulsions were characterized by an array of techniques including NMR,GPC,TEM,WAXD and DSC.The results indicate that the copolymers obtained are mostly block copolymers of polyethylene with random insertion of styrene units,and their M_W is in the range of 10~5-10~6.By enhancing the electron withdrawing of the s...

Synthesis, Crystal Structure and DNA Binding Studies of a Nickel(II) Complex with 2-Aminomethylbenzimidazole and Demethylcantharate

A new mixed-ligand nickel（Ⅱ） complex, [Ni（L）（DCA）（H2O）]·2H2O （L = C8H9N3, 2-aminomethyl-benzimidazole, DCA2- = 7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylate, demethylcantharate, C8H8O5）, has been synthesized and characterized. The structure of the complex was determined by single-crystal X-ray diffraction. It is of monoclinic system, space group P21/c with a = 7.7211（7）, b = 12.0799（12）, c = 19.7867（19）, β = 100.390（6）°, V = 1815.2（3） nm3, Dc = 1.625 g·cm-3, Ζ = 4, F（000） = 928, R = 0.0314 and wR = 0.0822. In addition, the interaction between the complex and DNA was studied by means of fluorescence spectra and viscosity. The results indicate that the complex binds to DNA by the mode of partial intercalation with the Stern-Volmer constants Ksv of 3.81 × 104 mol·L-1.

Synthesis, Crystal Structure and Thermal Stability of a Nickel(Ⅱ) Complex with Bicycle[2.2.1]-2-hepten-5,6-dicarboxylic Acid

The nickel complex {Ni（2,2-bipy）（H2O）3[C8H11O2（COO）]}（H2O）3 with bicycle-[2.2.1]-2-hepten-5,6-dicarboxylic acid [C7H8（COOH）2] and 2,2＇-bipyridine （bipy） as ligands has been synthesized and characterized. It crystallizes in monoclinic, space group P , with a = 0.74975（3）, b = 1.20309（4）, c = 1.30593（4） nm, α = 109.861（2）, β = 98.519（2）, γ = 90.575（2）o, V = 1.09337（7） nm3, Dc = 1.552 g/cm3, Z = 2, F（000） = 524, the final GOOF = 1.064, R = 0.0397 and wR = 0.1171. The crystal structure shows that the nickel ion is coordinated with four oxygen atoms from one bicycle[2.2.1]-2-hepten-5,6-dicarboxylic acid molecule and three water molecules and two nitrogen atoms from the 2,2′-bipyridine molecule, forming a distorted octahedral coordination geometry. The result of TG analysis shows that the title complex is stable under 200.0 ℃.

Hydrothermal Synthesis and Crystal Structure of a New One-dimensional Nickel(Ⅱ) Complex with 2-Pyridinecarboxyic Acid and 4,4′-Bipyridine Ligands

A new metal-organic coordination polymer [Ni[（2-pya）2（4,4′-bipy）]n·6nH2O （2-pya = 2-pyridinecarboxylic acid, 4,4′-bipy = 4,4′-pyridine） 1 has been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectrum, TG and single-crystal X-ray diffraction. The complex crystallizes in tetragonal, space group I4 1/α with a = b = 22.5642（19）, c = 10.7118（18） A, V = 5453.8（11） A^3, C22H28N4NiO10, Mr= 567.19, Dc = 1.382 g/cm^3, μ（MoKα） = 0.769 mm^-1, F（000） =2368, Z = 8, the final R = 0.0572 and wR = 0.1254 for 1401 observed reflections （I 〉 2σ（I））. It exhibits a one-dimensional chain-like structure by mixed ligands of 2-pyridinedicarboxylic acid and 4,4′-pyridine.

A Thermochemical Study on Complex Nickel(Ⅱ) L-α-Histidine

The formation enthalpy of complex nickel(Ⅱ) histidine(His) in water was determined by means of microcalorimetry in the temperature range of 298 15-323 15 K. The standard enthalpy of the formation of Ni(His) 2+ 2(aq) was calculated. On the basis of the experimental and the calculated results, three thermodynamic parameters(the activation enthalpy, the activation entropy and the activation free energy), the rate constants, three kinetic parameters(the apparent activation energy, the pre exponential constant and the reaction order) of the formation reaction of the title complex were obtained.

2-AMINOMETHYLPYRIDINE NICKEL(Ⅱ) COMPLEXES—SYNTHESIS,MOLECULAR STRUCTURE AND CATALYSIS OF ETHYLENE POLYMERIZATION

A series of new nickel(Ⅱ)complexes with 2-aminomethylpyridine ligands,(2-PyCH_2NHAr)_2NiBr_2(Ar=2,6- dimethylphenyl 2a;2,6-diisopropylphenyl 2b,2,6-difluorophenyl 2c),have been synthesized and used as catalyst precursors for ethylene polymerization in the presence of methylaluminoxane(MAO).The catalysts containing ortho-alkyl-substituents afford high molecular weight branched polyethylenes as well as a certain amount of oligomers.Enhancing the steric bulk of the alkyl substituent of the catalyst resulted in...

Synthesis and Catalytic Activity of Nickel(Ⅱ)and Cobalt(Ⅱ) Complexes Involving Chiral Leucinol

The title nickel complex I and cobalt complex II were obtained separately from the direct reaction of D-（＋）-leucinol with Ni（II） chloride and L-（-）-leucinol with Co（II） acetate tetra- hydrate in anhydrous methanol. The crystal structures of I and II were determined by single-crystal X-ray diffraction and further characterized by elemental analysis and IR. For I： [Ni（C18H45N3O3）]Cl2, orthorhombic, P212121, a = 11.2807（9）, b = 14.7115（11）, c = 16.3580（13） A, V = 2714.7（4） A3, Z = 4, Pcalcd = 1.177 Mg/m3, the final R = 0.0407, and 16539 reflections observed with I 〉 2σ（/）; For II： [Co（C45HI08N6015）], trigonal, R3：H, a = 23.981（3）, b =23.981（3）, c = 10.8925（15） A, γ = 120°, V = 5425.1（14） A3, Z = 3, Pcalcd = 1.002 Mg/m3, the final R = 0.0625 for 16556 observed reflections with I 〉 2σ（I）. The complexes were then used to catalyze the Henry reaction and obtained good catalytic results. The catalytic activity of the complexes was determined by IH NMR. And research is going towards the application to other organic reactions such as cyanosilylation reaction.

Synthesis and Crystal Structure of Nickel Complex of DSEN

The crystal of the title compound [Ni(dsen)]. EtOH, C32H32NiN2O5,Mr= 583. 33, (dsen = N, N'-disalicylidene-1, 2-dirnethoxyphenylethylenediamine) has been prepared and determined by X-ray single crystal diffraction. The crystal belongs to the orthorhombic space group Pbca with parameters: observab1e reflections.The result reveals that nickel ion is coordinated by two nitrogen atoms of azomethene and two phenoxy atoms of the ligand. The coordination geometry around the Ni(II) is close to a Square plane (D4h).

Synthesis,Crystal Structure and Fluorescence Property of a New Trinuclear Nickel(Ⅱ) Complex Bridged by 2,6-Pyridine Dicarboxylic Acid

A new trinuclear nickel complex,[Ni3（pdc）3（2,2＇-bipy）3（H2O）2]·2H2O（H2pdc = pyridine 2,6-dicarboxylic acid,2,2＇-bipy = 2,2＇-bipyridine） has been hydrothermally synthesized and characterized by IR,elemental analysis and X-ray diffraction methods.Crystal data for this complex：monoclinic,space group P21/n,a = 21.206（4）,b = 10.002（2）,c = 28.066（6）,β = 108.18（3）°,C51H41N9Ni3O16,Mr = 1212.06,V = 5.656（2） nm3,Dc = 1.423 g·cm-3,μ（MoKα） = 1.062 mm-1,Z = 4,F（000） = 2488,GOOF = 1.034,the final R = 0.0543 and wR = 0.1237 for 6149 observed reflections with Ⅰ 〉 2σ（Ⅰ）.In the complex,three nickel（Ⅱ） ions are bridged by the pyridine 2,6-dicarboxylic acid groups,and all nickel（Ⅱ） ions are seven-coordinated by nitrogen atoms of 2,2＇-bipyridine and pyridine 2,6-dicarboxylic acid and oxygen atoms from pyridine 2,6-dicarboxylic and water to adopt a severely distorted pentagonal bipyramidal geometry.The emission and excitation peaks of the complex in ethanol solutions are located at 336 and 316 nm,respectively.

Hydrothermal Synthesis, Crystal Structure and Properties of One Binuclear Nickel(Ⅱ) Complex with 3-(2-Pyridiyl)-1H-1,2,4-triazole

A new binuclear nickel（Ⅱ） complex [Ni_2（C_7 N_4 H_5）_3（C_9 H_9 O_2）]n has been hydrothermally synthesized with nickel sulfate, 3-（pyridin-2-yl）-1H-1,2,4-triazole and 3,5-dimethylbenzoic acid（3,5-DMBA）. It crystallizes in the triclinic space group P1 with a = 11.5769（7）, b = 12.3115（7）, c = 12.6431（7） A, α = 81.4860（10）o, β = 64.2830（10）o, γ = 63.7130（10）o, V = 1453.45（15） A^3, D_c = 1.604 g/cm^3, Z = 2, F（000） = 720, the final GOOF = 1.048, R = 0.0285 and wR = 0.0628. The crystal structure shows that the whole molecule consists of two nickel ions bridged by three μ_2-η~1：η~0-3-（pyridin-2-yl）-1,2,4-triazole anions. The coordination environment of Ni（Ⅱ） ion is NiO_2 N_4 and NiN_5, giving a distorted octahedral geometry and square pyramidal geometry respectively. The luminescence and thermal properties of the complex were investigated.

Chiral Resolution of β-dl-Phenylalanine Using Chiral Macrocyclic Nickel(Ⅱ) Complexes

The reactions of chiral four-coordinated nickel（Ⅱ） complex [Ni（RR-L）]（ClO4）2/[Ni（SS- L）]（ClO4）2 with β-dl-phenylalanine in acetonitrile/water gave a six-coordinated enantiomer of [Ni（RR-L）（β-d-HPhe）]（ClO4）2（1） and [Ni（SS-L）（β-l-HPhe）]（ClO4）2（2）, respectively（L = 5,5,7, 12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, HPhe = phenylalanine）. Single-crystal X-ray diffraction analyses revealed that the nickel（Ⅱ） atom displays a distorted octahedral coordination geometry by coordinating with four nitrogen atoms of L in a folded configuration, and two carboxylate oxygen atoms of β-d/l-HPhe in cis-position in both complexes. The monomers of [Ni（RR-L）（β-d-HPhe）]2＋ and [Ni（SS-L）（β-l-HPhe）]2＋ are connected through intermolecular hydrogen bonds to generate one-dimensional zigzag chains, respectively. The homochiral natures of 1 and 2 are confirmed by the results of CD spectroscopy.

Ethylene Oligomerization Promoted by Nickel Complexeswith 8-Iminoquinoline Derivatives

A series of 8-iminoquinoline derivatives nickel complexes were synthesized to proceed high activity in ethylene oligomerization.

Nickel Complexes Bearing Bidentate SchifF Base as Ethylene Oligomerization Catalysts

Several nickel complexes [N,N]NiBr_2, in which [N,N] indicates bidentatenitrogen-containing ligands (1: [N,N]=N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine(C_(18)H_(22)N_2); 2: N-(2,6-diisopropylphenyl)-6-methylpyridine-2-carboxaldimine (C_(19)H_(24)N_2);3: N-(2,4,6-trimethylphenyl)pyridine-2-carboxaldimine(C_(15)H_(16)N_2); 4:N-(2,4,6-trimethylphenyl)-6-methylpyridine-2-carboxaldimine (C_(16)H_(18)-N_2) were synthesized.Some of the nickel complexes exhibit high activity for ethylene oligomerizatiori in the presence ofan organoaluminum activator. The main factor affecting the activity and the structure of oligomersis the steric effect of substituents on [N,N] ligands. Methylaluminoxane (MAO) -activated catalystsshowed higher activities and produced oligomers with higher molecular weight than Et_2AlCl-activatedones. The oligomerization in toluene rather than hexane results in much higher activity, and theoligomers produced in toluene have relatively high molecular weight. With activation of MAO orEt_2AlCl, the [N,N]NiBr_2 system tended to produce highly branched oligomers with low α-olefincontent, but the α-olefin content could be increased by changing the reaction conditions.

Synthesis and Characterization of Nickel(II) Complex Bearing 2,9-di-tert-butyl-1,10-phenanthroline Ligand

The complex DtbpNiCl2（Dtbp = 2,9-di-tert-butyl-1,10-phenanthroline） was synthe- sized and characterized by X-ray single-crystal structure analysis. For the complex： C20 H24 Cl2 N2 Ni CH2 Cl2, Mr = 506.95, monoclinic, space group P21 /c, a = 9.5905（3）, b = 13.7587（3）, c = 17.3364（5）, β = 94.244（2）°, V = 2281.31（11）3, Z = 4, Dc = 1.476 g/cm3, λ = 1.54184, μ = 5.606 mm-1, F（000） = 1048, S = 1.079, R = 0.0402 and wR = 0.1010 for 3223 observed reflections with I 〉 2σ（I）. In complex DtbpNiCl2, the nickel adopts a distorted tetrahedral geometry coordinated by two nitrogen atoms of Dtbp and two chlorine ions. The complex is connected by intermolecular C–H…Cl hydrogen bonds to form a 1D structure in the solid state.

Crystal Structure and Characterization of 2-N-(2-Hydroxy-benzylidene) Furanmethanoamine Nickel(II) Complex

The Ni（Ⅱ） complex with ligand 2-N-（2-hydroxy-benzylidene） furanmethanoamine has been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group C2/c with a = 2.0280（4）, b =0.57700（12）, c = 1.7340（4） nm, β = 94.74（3）°, Z = 4, Dc = 1.508 g/cm^3, the final R = 0.0434 and wR = 0.1112 for 1843 observed reflections with 1 〉 2σ（I）. X-ray analysis revealed that the Ni（Ⅱ） ion is coordinated by two nitrogen atoms of Schiff base and two oxygen atoms of salicylaldehyde in the equatorial plane, and the coordination geometry can be described as a square.

Synthesis,Crystal Structure and Characterization of a Nickel Complex Based on Phenoxyimine Ligand and Catalysis of the Vinyl Polymerization of Norbornene

The title complex N,O-bis{2-[[（2-benzhydryl-4,6-dimethylphenyl）imino]-methyl]-phenol}-nickel（II）（C56H48N2NiO2） has been synthesized by the reaction of 2-[[（2-benzhydryl-4,6-dimethylphenyl）mino]-methyl]-phenol with Ni（CH3COO）2·4 H2O, and characterized by elemental analysis and IR spectrum. The spatial structure of the complex has been confirmed by single-crystal X-ray diffraction analysis. The compound belongs to the monoclinic system, space group C2/c with a = 39.035（8）, b = 13.276（3）, c = 17.679（4） A°, β = 98.06（3）°, V = 9071（3） A°^3, C56H48N2NiO2, Mr = 839.67, Z = 8, Dc = 1.230 Mg/m^3, μ = 0.472 mm^-1, F（000） = 3536, T = 293（2） K, the final R = 0.0675 and w R = 0.1345（I 〉 2s（I））. The compound showed excellent catalytic activity up to 1.268 × 10^7 g of PNB（mol of Ni）^-1h^-1 for the addition polymerization of norbornene by using methylaluminoxane（MAO） as a cocatalyst.

Synthesis and Crystal Structure of a New Nickel(II) Complex with Unsymmetric Quadridentate Schiff Base Containing Oxime

The title complex, C18H15N3NiO3, has been prepared and characterized by X-ray diffraction analysis. It crystallizes in the monoclinic system, space group Cc with a = 10.939(2), b = 22.909(5), c = 6.907(1) ?, β = 116.75(3)°, V = 1545.7(5) ?, Z = 4, Mr = 380.04, F(000) = 784, Dc = 1.633 g/cm3 and μ(MoKα) = 1.279 mm–1. The structure was refined to R = 0.0472 and wR = 0.0893 for 2571 observed reflections with I > 2σ(I). The absolute structure Flack parameter X is 0.01(2). In this crystal structure, strong face-to-face π-π stacking interactions between adjacent molecules lead to a one-dimensional chain structure.

Synthesis, Crystal Structure and Electrochemistry Properties of a (N,N'-Ethylene-bis(salicylaldiminato)) Nickel(II) Complex, [Ni_2(salen)_2]·NCS·NH_4

A new Ni（Ⅱ） complex [Ni2（salen）2]·（NCS）·NH4 （salen = N,N＇-bis（salicylideneamino）ethanato） has been prepared and structurally characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group Pbca with a = 16.8725（13）, b = 19.0046（15）, c = 20.0583（16）A, Z = 8, V = 6431.8（9）A^3, C33H32N6Ni2O4S1, Mr = 726.13, Dc = 1.500 g/cm^3, F（000） = 3008, μ = 1.284 mm^-1, the final R = 0.0394 and wR = 0.0767 for 4449 observed reflections with I 〉 2σ（I）. The complex involves a N,N＇-ethylene-bis（salicylaldiminato） Schiff base, an isothiocyanato anion and an ammonium cation. The nickle（II） ion adopts a distorted square coordination geometry with N2O2 set of Schiff base ligand. The complexes are linked into a dimmer via intermolecular hydrogen bonds and the [Ni（salen）] moieties are connected together to form a 2-D layer structure by intermolecular N-H…O hydrogen bonds and π-π stacking. Cyclic-voltammetry method was used to characterize electrochemically the complex.

Syntheses, Crystal Structures and Photoluminescence Properties of Cadmium(Ⅱ) and Nickel(Ⅱ) Complexes with 2-(2-Benzimidazolyl)quinoline

Two novel complexes, [Cd2（BMQU）2Cl4] （1） and [Ni（BMQU）2HPO4]·1.5H2O （2） （BMQU = 2-（2-benzimidazolyl）quinoline）, were synthesized by the hydrothermal method and characterized by elemental analysis, IR, and TG-DTG. The crystal structures were determined by single-crystal X-ray diffraction. Both 1 and 2 crystallize in the triclinic system, space group P . The data for 1： a = 0.8342（7）, b = 0.9226（9）, c = 1.0646（8） nm, α = 90.819（2）, β = 97.466（2）, γ = 98.280（2）°. The Cd（Ⅱ） is coordinated with three chlorine atoms and two nitrogen atoms of a BMQU molecule, generating a distorted square-pyramidal geometry. The dinuclear Cd（Ⅱ） complex is formed by two chlorine bridge bonds, and the one-dimensional chain structure is constructed with the hydrogen bond N-H…Cl and π-π stacking interaction. The data for 2： a = 1.2251（1）, b = 1.2451（1）, c = 1.2868（1） nm, α = 107.510（2）, β = 98.630（1）, γ = 109.921（2）°. The Ni（Ⅱ） is coordinated with four nitrogen atoms of two BMQU molecules and two oxygen atoms of a HPO42-, forming a distorted-octahedral geometry. The two-dimensional layer structure is formed by the hydrogen bonds and π-π stacking interaction between neighboring molecules. Complex 1 shows a strong blue fluorescence emission （λmax= 456 nm） at solid state.

MAGNETIC INVESTIGATION OF THE NICKEL COMPLEXES OF MULTI－SULFUR 1．2－DITHIOLATES

The magnetic susceptibility of (Bu4N)(NI(MEDT)2) and (Bu4N)(Ni(PHDT)2)(MEDT:5-methyl-6-hydro-1, 4-dithiin-2, 3-dithiolate, PHDT: 5-phenyl-6-hydro-1.4-dithiin- 2,3-dithiolate) was measured in the temperature range of 75-300K. The magnitudeof magnctic moments is consistent,with a doublet state arising from Ni(Ⅲ).Antiferromagnetic properties were discussed in consideration of molecularstructure.