A series of bridged ligand 4,4′-methylene-bis [2,6-dialkyl-N-(2-phenylmethylene)-anil] was efficiently synthesized by the condensation reaction of 4,4′-methylene-bis(2,6-disubstituted aniline) and salicyl aldehyde.T...A series of bridged ligand 4,4′-methylene-bis [2,6-dialkyl-N-(2-phenylmethylene)-anil] was efficiently synthesized by the condensation reaction of 4,4′-methylene-bis(2,6-disubstituted aniline) and salicyl aldehyde.They easily coordinated with Ni (Ⅱ) to form the title complexes,which were characterized by IR spectroscopy and elemental analysis.The complexes show good activities for vinyl polymerization of norbornene with methylalumoxane (MAO) as co-catalyst.The variations of complexes and catalytic parameters were investigated along with viscosimetric measurement of resultant polynorbornenes.展开更多
A series of chiral and achiral bis(2-oxazolinylphenolato)nickel(II) complexes 2 were synthesized by reactions of various 2-(4,5-dihydro-2-oxazolyl)phenol derivatives with nickel chloride hexahydrate. The molecular str...A series of chiral and achiral bis(2-oxazolinylphenolato)nickel(II) complexes 2 were synthesized by reactions of various 2-(4,5-dihydro-2-oxazolyl)phenol derivatives with nickel chloride hexahydrate. The molecular structure of complex 2a was determined by X-ray single crystal diffraction. The crystal of complex 2a was monoclinic, space group P21 with cell dimension of a=1.1121(4) nm, b=0.9472(3) nm, c=1.4113(5) nm, ==90, =91.450(6), V=1.4861(8) nm3, Z=2, and =0.693 mm—1. In the solid state, the nickel(II) ion was in a square-planar coordination geometry. The catalytic activities of complexes 2 in Baeyer-Villiger reaction with molecular oxygen were investigated.展开更多
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-methylp...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.展开更多
A series of nickel（II） complexes have been synthesized and characterized. Molecular structure analysis exhibits that a square planar geometry around nickel is adopted. Upon activation with MAO, these nickel（II） co...A series of nickel（II） complexes have been synthesized and characterized. Molecular structure analysis exhibits that a square planar geometry around nickel is adopted. Upon activation with MAO, these nickel（II） complexes are efficient in catalyzing the ethylene dimerization, providing 1-butene with an activity of up to 1.4 ×10^7 g/（molohoatm）. The heteroatoms of the sidearm in the complexes were proved to have great impact on the activity and selectivity of 1-butene.展开更多
The bis(N-ethyl-5-methylsalicylaldimine)nickel(II) [Ni(5-me-saletN)2] complex was synthesized and characterized by elemental analyses, FT-IR, TG-DTA, mass spectrometry and vapour pressure measurement studies. The TG c...The bis(N-ethyl-5-methylsalicylaldimine)nickel(II) [Ni(5-me-saletN)2] complex was synthesized and characterized by elemental analyses, FT-IR, TG-DTA, mass spectrometry and vapour pressure measurement studies. The TG curve of the complex showed a single-step weight loss commencing from 490 K to nil residue at 600 K, without competing fragmentation step. The non-isothermal vaporization activation energy value determined by Coats-Redfern method yielded the value of 93.5 ± 7 kJmol–1. The dynamic TG run proved the complex to be completely volatile. And the equilibrium vapour pressure of the complex over the temperature range of 421 - 524 K, determined by the TG-based transpiration technique yielded the value of 94.2 ± 1.2 kJmol–1 for its standard enthalpy of vaporization . The entropy of vaporization was calculated from the intercept and found to be 249.4 ± 2.6 Jmol–1•K–1.展开更多
Hydrogen adsorption and storage on Ni-decorated CNC has been investigated by using DFT. A single Ni atom decorated CNC adsorbs up to six H2 with a binding energy of 0.316 eV/H2. The interaction of 3H2 with Ni-CNC is i...Hydrogen adsorption and storage on Ni-decorated CNC has been investigated by using DFT. A single Ni atom decorated CNC adsorbs up to six H2 with a binding energy of 0.316 eV/H2. The interaction of 3H2 with Ni-CNC is irreversible at 603 K. In contrast, the interaction of 4H2 with Ni-CNC is reversible at 456 K. Further characterizations of the two reactions are considered in terms of the projected densities of states, electrophilicity, and statistical thermodynamic stability. The free energy of the reaction between 4H2 and Ni-CNC, surface coverage and rate constants ratio meet the ultimate targets of DOE at 11.843 atm, 0.925 and 1.041 respectively. The Ni-CNC complexes can serve as high-capacity hydrogen storage materials with capacities of up to 11.323 wt.%. It is illustrated that unless the access of oxygen to the surface is restricted, its strong bond to the decorated systems will preclude any practical use for hydrogen storage.展开更多
文摘A series of bridged ligand 4,4′-methylene-bis [2,6-dialkyl-N-(2-phenylmethylene)-anil] was efficiently synthesized by the condensation reaction of 4,4′-methylene-bis(2,6-disubstituted aniline) and salicyl aldehyde.They easily coordinated with Ni (Ⅱ) to form the title complexes,which were characterized by IR spectroscopy and elemental analysis.The complexes show good activities for vinyl polymerization of norbornene with methylalumoxane (MAO) as co-catalyst.The variations of complexes and catalytic parameters were investigated along with viscosimetric measurement of resultant polynorbornenes.
基金Project supported by the Special Funds for Major State Basic Research Projects (No. 1999064801) the National Natural Science Foundation of China (Nos. 20072004 and 20372022) and the Research Fund for the Doctoral Program of Higher Education (No. 2002
文摘A series of chiral and achiral bis(2-oxazolinylphenolato)nickel(II) complexes 2 were synthesized by reactions of various 2-(4,5-dihydro-2-oxazolyl)phenol derivatives with nickel chloride hexahydrate. The molecular structure of complex 2a was determined by X-ray single crystal diffraction. The crystal of complex 2a was monoclinic, space group P21 with cell dimension of a=1.1121(4) nm, b=0.9472(3) nm, c=1.4113(5) nm, ==90, =91.450(6), V=1.4861(8) nm3, Z=2, and =0.693 mm—1. In the solid state, the nickel(II) ion was in a square-planar coordination geometry. The catalytic activities of complexes 2 in Baeyer-Villiger reaction with molecular oxygen were investigated.
基金This work was subsidized by Special Funds for Major State Basic Research Projects of China(No.G1999064801).
文摘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.
文摘A series of nickel（II） complexes have been synthesized and characterized. Molecular structure analysis exhibits that a square planar geometry around nickel is adopted. Upon activation with MAO, these nickel（II） complexes are efficient in catalyzing the ethylene dimerization, providing 1-butene with an activity of up to 1.4 ×10^7 g/（molohoatm）. The heteroatoms of the sidearm in the complexes were proved to have great impact on the activity and selectivity of 1-butene.
基金supported by the Natural Science Foundation of Heilongjiang Province of China(No.B2015015)the Post-doctoral Scientific Research Developmental Fund of Heilongjiang Province of China(No.LBH-Q14158)the Program for Yong Teachers Scientific Research in Qiqihar University(No.2014k-Z07)
文摘The bis(N-ethyl-5-methylsalicylaldimine)nickel(II) [Ni(5-me-saletN)2] complex was synthesized and characterized by elemental analyses, FT-IR, TG-DTA, mass spectrometry and vapour pressure measurement studies. The TG curve of the complex showed a single-step weight loss commencing from 490 K to nil residue at 600 K, without competing fragmentation step. The non-isothermal vaporization activation energy value determined by Coats-Redfern method yielded the value of 93.5 ± 7 kJmol–1. The dynamic TG run proved the complex to be completely volatile. And the equilibrium vapour pressure of the complex over the temperature range of 421 - 524 K, determined by the TG-based transpiration technique yielded the value of 94.2 ± 1.2 kJmol–1 for its standard enthalpy of vaporization . The entropy of vaporization was calculated from the intercept and found to be 249.4 ± 2.6 Jmol–1•K–1.
文摘Hydrogen adsorption and storage on Ni-decorated CNC has been investigated by using DFT. A single Ni atom decorated CNC adsorbs up to six H2 with a binding energy of 0.316 eV/H2. The interaction of 3H2 with Ni-CNC is irreversible at 603 K. In contrast, the interaction of 4H2 with Ni-CNC is reversible at 456 K. Further characterizations of the two reactions are considered in terms of the projected densities of states, electrophilicity, and statistical thermodynamic stability. The free energy of the reaction between 4H2 and Ni-CNC, surface coverage and rate constants ratio meet the ultimate targets of DOE at 11.843 atm, 0.925 and 1.041 respectively. The Ni-CNC complexes can serve as high-capacity hydrogen storage materials with capacities of up to 11.323 wt.%. It is illustrated that unless the access of oxygen to the surface is restricted, its strong bond to the decorated systems will preclude any practical use for hydrogen storage.
