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,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.

The Synthesis and Absorption Character of New Bis (dithiobenzil) nickel Complex NIR Dyes

A series of new NIR dyes bearing 4-(4-morpholinyl) phenyl and substituted phenyl, were synthesized. The maximum absorption wavelengths of these dyes range from 928 nm to 990 nm.

Supramolecular Formation via Hydrogen Bonding in Copper and Nickel Complexes with 2-Hydroxynicotinic Acid

Two complexes, Cu（HnicO）2 1 and Ni（HnicO）2（H2O）2 2 （H2nicO = 2-hydroxynicolinic acid）, were synthesized by hydrothermal reactions and structurally characterized. Complex 1 crystallizes in monoclinic, space group P21/n, with a = 8.314（7）, b = 6.275（4）, c = 11.283（7）A, β = 98.32（3）°, V = 582.5（7）A^3, Z = 2, Mr = 339.74, Dc = 1.937 g/cm3, F（000） = 342, μ = 1.908 mm^-1, S = 1.097, the final R = 0.0284 mad wR = 0.0781 for 1177 observed reflections with Ⅰ 〉 2σ（Ⅰ）. Complex 2 crystallizes in monoclinic, space group P21/c, with a = 7.438（5）, b = 12.22（1）, c = 7.537（5）A,β = 100.07（3）°, V= 674.3（8）A3, Z = 2, Mr = 370.95, Dc = 1.827 g/cm^3, F（000） = 380, = 1.487 mm^-1, S = 1.041, the final R = 0.0335 and wR = 0.0779 for 1202 observed reflections with I 〉 2σ（Ⅰ）. There are extended 3D framework structures in complexes 1 and 2 due to the N-H…O and C-H…O hydrogen bonds. The copper atom in 1 has square planar coordination, while the nickel atom in 2 adopts octahedral coordination geometry. The TG curve shows that complex 2 is stable in solid state to 150 ℃.

Solvothermal Synthesis,Crystal Structure and Antimicrobial Activity of a Novel Imide Nickel Complex [Ni(CH_3CONCOCH_3)_2·2(H_2O)]

A novel imide nickel complex [Ni（CH3CONCOCH3）2·2（H2O）] was synthesized by the solvothermal reaction of nickel acetate tetrahydrate and acetonitrile.What amazed us is that acetonitrile had changed into acetyl imide in enol form during the formation process of the title complex.The complex was characterized by elemental analysis,IR spectrum and X-ray single-crystal diffraction analysis.It crystallizes in the orthorhombic system,space group Pbca with a = 7.4503（7）,b = 13.1089（12）,c = 14.1303（14）,V = 1380.0（2）3,Dc = 1.420 g/cm3,Mr = 294.94,Z = 4,F（000） = 616,μ = 1.422 mm-1,the final R = 0.0487 and wR = 0.1482.The four-coordinated nickel（II） center is surrounded by 4O atoms from two imide ligands and has a distorted square planar geometry.The complex is connected to form a supramolecule with an infinite three-dimensional network through intramolecular and intermolecular hydrogen bonds.Antimicrobial activity was investigated by agar diffusion method,and the result showed that the complex was active against coli bacillus,staphylococcus aureus and bacillus subtilis.The thermal stability of the title complex was also studied by TG-DTA method.

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).

Unexpected Synthesis and Crystal Structure of Macrocyclic Nickel Complex Involving Rare S-Cl Bond

A novel complex of [NiL（OOCNH2C2H3SClO3）]·H2O was obtained unexpectedly by the reaction of [Ni（rac-L）]（ClO4）2 with l-cysteine （L=5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra- azacyclotetradecane）, and characterized by EA, IR, ESI-MS and single-crystal X-ray diffraction. It crystallizes in the orthorhombic system, space group P212121 with a=9.211（12）, b=14.942（19）, c=19.002（2）, Mr=563.80, V=2615.3（6）3 , Z=4, Dc=1.432 g/cm3 , F（000）=1204, μ=0.966 mm-1 , the final R=0.0565 and wR=0.1515. The central nickel（Ⅱ） ion displays a distorted six-coordinate octahedral coordination geometry by coordination with four nitrogen atoms of L, and one oxygen and one nitrogen atoms of l-cysteine. The sulfur atom of l-cysteine instead of oxygen atom links directly with the chlorine atom of perchlorate. The title complex is the first example of perchlorate salt involving the sulfur atom.

Simple Preparation of Halogen-Substituted <i>α</i>-Diimine Nickel Complexes Immobilized into Clay Interlayer as Catalysts for Ethylene Oligo-/Polymerization

In the practical use for the production of the α-olefins, it is highly desired to develop a novel heterogeneous catalyst system. The metal complexes immobilized into the clay interlayers show a great potential as heterogeneous catalysts due to their excellent processability. In this study, nine types of heterogeneous procatalyst Ln/Ni2+-micas were synthesized via a one-pot preparation method, which includes both the condensation reaction of the ligand derivatives and the intercalation of the ligands into the Ni2+ ion-exchanged fluorotetrasilicic mica interlayer. The ligand structures of the prepared procatalysts were [Ln: R-N = C(Nap)-C(Nap) = N-R] [(Nap = 1,8-naphthdiyl) (L1, R = 2-MePh;L2, R = 2-FPh;L3, R = 2-BrPh;L4, R = 4-MePh;L5, R = 4-FPh;L6, R = 4-BrPh;L7, R = 2,4-F2Ph;L8, R = 2,4-Br2Ph;L9, R = 2,6-F2Ph). At 50℃ and 0.7 MPaethylene pressure, the triisobutylaluminum-activated L1-L6/Ni2+-mica showed a catalytic activity for the ethylene oligo-/polymerization in the range of 334 - 549 g-ethylene&bull;g-cat–1&bull;h–1. A high catalyst activity was obtained when the substituent having a larger steric bulk than that of a methyl substituent was introduced at the ortho-position of the aryl rings. The introduction of the fluorine substituent as a strong electron-withdrawing group to the para-position also increased the catalytic activity. The L2, L4, L5, and L6/Ni2+-micas showed moderate selectivities to oligomers consisting of C4-C20 in the range of 19.9 - 41.6 wt% at 50℃. The calculated Schulz-Flory constants α based on the mole fraction of C12 and C14 were within 0.61 - 0.78.

Nickel catalysts with asymmetric steric hindrance for ethylene polymerization

α-Diimide catalysts have attracted widespread attention due to their unique chain walking characteristics.A series ofα-diimide nickel/palladium catalysts with different electronic effects and steric hindrances were designed and synthesized for olefin polymerization.In this work,we synthesized a series of asymmetricα-diimide nickel complexes with different steric hindrances and used them for ethylene polymerization.These nickel catalysts have high ethylene polymerization activity,up to 6.51×10^(6)g·mol^(−1)·h^(−1),and the prepared polyethylene has a moderate melting point and high molecular weight(up to 38.2×10^(4)g·mol^(−1)),with a branching density distribution between 7 and 94 branches per 1000 carbons.More importantly,the polyethylene prepared by these catalysts exhibits excellent tensile properties,with strain and stress reaching 800%and 30 MPa,respectively.

Nickel Complexes Based on Salicylaldehyde-imine Ligands： Synthesis, Characterization and Catalytic Oligomerization of Ethylene

A series of nickel complexes {NOONR}Ni（A： R=Me; B： R=t-Bu; C： R=OMe） based on salicylalde- hyde-imine ligands was synthesized through Schiff base condensation and metal complexation reaction. Upon activation with methylalurninoxane（MAO）, nickel complexes A--C all exhibited good catalytic activity[turnover frequency=5.2×10^5-16.3×10^5 g/（mol Ni-h）] and oligomer selectivity（above 85%, mass fraction） in ethylene oligomerization. In addition, C8--C12 olefins occupied an important proportion in the products of oligomers. Under the conditions of 4.0 MPa, 25℃ and A1/Ni molar ratio of 275, the catalytic selectivity of A/MAO system toward C8-C12 was about 30. 1%（mass fraction）, and the content of C8--C12 a-olefins was consistently above 70%. Furthermore, besides the ligand environment, the catalytic properties of A-C were substantially affected by experimental parameters, such as the reaction pressure, reaction temperature and A1/Ni ratio.

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, Characterization and Ethylene Oligomerization Behavior of Neutral Nickel Complexes Bearing N-Fluorinated Phenyl Salicylaldiminato Chelate Ligands

A series of neutral nickel complexes featuring N-fluorinated phenyl salicylaldiminato chelate ligands was syn- thesized, and the novel molecular structure of complex C14 was further confirmed by X-ray crystallographic analy- sis. The neutral nickel complexes showed high activity up to 9.96× 10^5 g oligomers/（mol Nioh） and high selectivity of C6 in catalyzing ethylene oligomerization using methylaluminoxane （MAO） as cocatalyst. It was observed that the strong electron-withdrawing effect of the fluorinated salicylaldiminato ligand was able to significantly increase the catalytic activity for oligomerization of ethylene. In addition, the influence of reaction parameters such as A1/Ni molar ratio, reaction temperature, a variety of cocatalyst and ethylene pressure on catalytic activity was investigated.

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.

Asymmetric transfer hydrogenation of ketones catalyzed by nickel complex with new PNO-type ligands

The new polydentate mixed-N,P,O chiral ligands have been synthesized by the condensation of bis（o-formylphenyl）- phenylphosphane and R-phenylglycinol in CHCl_3,and fully characterized by IR,NMR and EIMS spectra.These ligands were employed with a simple Ni complex Ni（PPh_s）_2Cl_2 in situ as catalytic systems for asymmetric transfer hydrogenation of ketones,and the corresponding optical alcohols were obtained with up to 84%ee under mild conditions.

Nickel (Ⅱ) Complex Catalyzed Conjugate Addition Reaction of Functionalised Organozinc Reagents to α,β -Unsaturated Esters

Functionalized organozinc reagents can easily under 1, 4-addition reaction withunsaturated esters in the presence of catalytic amount of Ni (acac)_2 and tertiary ammes under verymild conditions to give the products in excellent yields.

Syntheses, Characterization and Magnetism of μ-2-Chloroterephthalato Nickel (Ⅱ) Binuclear Complexes

Three new nickel(Ⅱ) binuclear complexes, namely,[Ni_2(CTPHA)(Phen)_4](ClO_4)2·4H_2O (complex 1 ), [Ni_2(CTPHA) (Nphen)_4](ClO_4)_2·2H_2O(complex 2 ) and [Ni2 (CTPHA)(Bpy)4] (ClO4)2 (complex 3 ). (CTPHA = 2-chloroterephthalate . Phen=1, 10-phenanthroline, Nphen=5-nitro-1, 10-phenanthroline, Bpy=2, 2-bipyridyl), have been synthesized and characterized by elemental analysis, IR, molar conductance and electronic spectra. These complexes are proposed tohave extended Z-chloroterephthalato-bridged structure and to consist of two nickel(Ⅱ). The variable-temperature magnetic susceptibilities of complex 1 were measuredover 4. 2～300 K and the data were fitted by least-squares to a susceptibility equationderived from the Hamiltonian operator, giving the exchange integral ZJ=1. 6 cm-1, which indicate a very weak antiferromagnetic interaction between nickelf (Ⅱ) ions.

Synthesis, Crystal Structure and Nonlinear Optical Properties of Nickel(Ⅱ) Complex with Schiff-base Ligand

The nickel(Ⅱ) complex with the new ligand of S-benzyl-b-N-[10-ethyl- phenothiazine-3-methylene]dithiocarbazate(HL) crystallizes in the triclinic system, space group P?with a = 7.516(1), b = 11.322(1), c = 13.366(1) , a = 84.818(1), b = 81.688(1), g = 76.037(1), V = 1090.26(3) 3, Z = 1, Dc = 1.413 g/cm3, F(000) = 482, m(MoKa) = 0.774 mm-1 (l = 0.7103 ?, R = 0.0573 and wR = 0.1375 for 3357 observed reflections with I ≥ 2s(I). The HL has lost a proton from its tautomeric thiol form and acts as a single negatively charged bidentate ligand coordinating to the nickel ion via the mercapto sulfur and b-nitrogen atoms. The geometry around Ni(Ⅱ) is almost square-planar with two equivalent NiN and NiS bonds. The nonlinear absorption of HL and NiL2 solutions (in DMF) was measured by open-aperture Z-scan technique at the wavelength of 532 nm.

Synthesis, Structure and Norbornene Polymerization Catalyzed by Nickel(Ⅱ) Complex Bearing N,O-bis(1-(6-ethylpyridin-2-ylimino)-methylenyl)naphthalen-2-ol Ligand

The title complex bis{1-{[（6-ethyl-2-pyridinyl）imino]methylenyl}-2-naphthale- nolato-N,O}-nickel（lI） （C36H32NnO2Ni） has been synthesized by the reaction of l-{[（6-ethyl-2- pyridinyl）imino]methylenyl}-2-naphthalenol with Ni（CH3COO）2·4H2O, and characterized by IR spectrum, elemental analysis and TG. The complicated space structure has been confirmed by single-crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21/c with a = 11.410（4）, b = 14.382（4）, c = 18.121（6） ,A, β = 97.147（6）% V= 2950.5（16）A3, C36H32N4O2Ni, Mr = 611.37, Z = 4, Dc = 1.376 g/cm3, μ = 0.698 mm-1 F（000） = 1280, the final R = 0.0519 and wR = 0.1493 （1 〉2σ（I））. This title compound was used as precatalysts for the polymerisation of norbornene. When activated with MAO, the complex exhibited excellent catalytic activity up to 1.98 × 107 g ofPNB （mol of Ni）-1 h-1 with high monomer conversion.