Wei Gao

Jilin University, Yung-chi, Jilin Sheng, China

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Publications (76)179.63 Total impact

  • Journal of Alloys and Compounds 10/2014; 611:24–29. · 2.73 Impact Factor
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    ChemInform 01/2014; 45(1).
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    ABSTRACT: A series of tridentate anilido-imine [N,N,O] ligands 2-(2-(R12-2,6-C6H3NH)C6H4)HC═N(4-tBu-6-R2-C6H2OH) [R1 = Me, R2 = tBu (LaH2); R1 = Et, R2 = tBu (LbH2); R1 = iPr, R2 = tBu (LcH2); R1 = Me, R2 = Ad (LdH2); R1 = Et, R2 = Ad (LeH2); R1 = iPr, R2 = Ad (LfH2)] were synthesized and characterized. Reaction of the free ligand LdH2 with TiCl4 in toluene at low temperature affords the zwitterionic complex Ld+H2Ti–Cl4 (1d). The zwitterionic complex can be dissolved in THF to form THF-solvated complex 1d′. Heating 1d in toluene at 40 °C affords the neutral complex LdHTiCl3 (2d) by losing a HCl. Complex 2d can be fully converted to the final complex LdTiCl2 (3d) at 140 °C under vacuum by losing another HCl. Complexes 3a–3c, 3e, and 3f were also synthesized in high yields in the same one-pot procedure. All complexes were characterized by 1H and 13C NMR spectroscopy, and the molecular structures of 1d′, 3b, 3d, and 3e were determined by single-crystal X-ray diffraction analysis. The titanium centers in complexes 3b, 3d, and 3e are five-coordinated with a geometry situated between trigonal bipyramid and square pyramid. Upon activation with alkylaluminum and Ph3C+B(C6F5)4–, complexes 3a–3f exhibit moderate catalytic activity for ethylene polymerization.
    Organometallics 10/2013; 32(21):6277–6285. · 4.15 Impact Factor
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    ABSTRACT: Apatite-type lanthanum silicate (ATLS) electrolyte coatings for use in intermediate-temperature solid oxide fuel cells were deposited by atmospheric plasma spraying (APS). Plasma-sprayed coatings with typical composition La10(SiO4)6O3 exhibiting good densification and high oxide ionic conductivity were obtained by properly adjusting the spraying parameters, particularly the gun current. The highest obtained ionic conductivity value of 3.3 mS/cm at 1,173 K in air is comparable to other ATLS conductors. This work demonstrated empirically that utilization of the APS technique is feasible to synthesize dense La10(SiO4)6O3 electrolyte coatings using gun currents within an unusually broad range.
    Journal of Thermal Spray Technology 10/2013; · 1.48 Impact Factor
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    ABSTRACT: A series of new half-sandwich titanium(IV) complexes che late d w ith 2 -(tetrame thylcyclope nt adie ny l)-benzylamido ligands, 2-Me 4 CpC 6 H 4 CH 2 (R)NTiCl 2 (R = i Pr ( 1 ), Cy ( 2 ), n Pr (3 ), 4-MePh ( 4 )), have been synthesized from the chlorotrimethylsilane elimination reactions of TiCl 4 with the double-trimethylsilyl-substituted preligands 2-Me 4 (TMS)-CpC 6 H 4 CH 2 (R)N(TMS) (R = i Pr (TMS 2 L1), Cy (TMS 2 L2), n Pr (TMS 2 L3), 4-MePh (TMS 2 L4)). The free ligands H 2 L1− H 2 L4were synthesized by reduction of the corresponding imine compounds 2-Me 4 CpHC 6 H 4 CHNR with LiAlH 4 , while the imine compounds were formed in situ by a condensation reaction of 2-tetramethylcyclopentadienylbenzaldehyde with the corresponding amine. The free ligands were characterized by LC-MS and 1 H NMR spectroscopy, and the titanium complexes were characterized by 1 H and 13 C NMR, elemental analyses, and single-crystal X-ray crystallography. The X-ray crystallography analysis reveals that these titanium complexes possess a three-legged piano-stool geometry with the amide N atom in a mitered six-membered chelating ring and the two chloride atoms as the legs. The angle between the cyclopentadienyl plane and the attached phenyl plane in these complexes (59.2, 62.7, and 61.9 ° for complexes 1, 2, and 4 , respectively) is much less than 90 ° in the solid state. Upon activation with Al i Bu 3 and Ph 3 CB(C 6 F 5 ) 4 , complexes 1− 4 exhibit reasonable catalytic activity for ethylene homopolymerization and copolymerization with 1-hexene at 110 ° C, producing high-molecular-weight polyethylenes and poly(ethylene- co -1-hexenes) with relatively high comonomer incorporation. Complex 4 was found to show higher catalytic activity for ethylene/1-hexene copolymerization than complexes 1−3 under similar conditions, while complexes 1− 3 produce poly(ethylene- co -1-hexenes) with higher comonomer incorporation.
    Organometallics 07/2013; 32(15):4185. · 4.15 Impact Factor
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    ABSTRACT: A series of NCO/NCS pincer precursors, 3-(Ar(2) OCH2 )-2-Br-(Ar(1) NCH)C6 H3 (((Ar1) NCO(Ar2) )Br, 3 a-3 d) and 3-(2,6-Me2 C6 H3 SCH2 )-2-Br-(Ar(1) NCH)C6 H3 (((Ar1) NCS(Me) )Br, 4 a and 4 b) were synthesized and characterized. The reactions of [(Ar1) NCO(Ar2) ]Br/ [(Ar1) NCS(Me) ]Br with nBuLi and the subsequent addition of the rare-earth-metal chlorides afforded their corresponding rare-earth-metal-pincer complexes, that is, [((Ar1) NCO(Ar2) )YCl2 (thf)2 ] (5 a-5 d), [((Ar1) NCO(Ar2) )LuCl2 (thf)2 ] (6 a, 6 d), [((Ar1) NCO(Ar2) )GdCl2 (thf)2 ] (7), [{((Ar1) NCS(Me) )Y(μ-Cl)}2 {(μ-Cl)Li(thf)2 (μ-Cl)}2 ] (8, 9), and [{((Ar1) NCS(Me) )Gd(μ-Cl)}2 {(μ-Cl)Li(thf)2 (μ-Cl)}2 ] (10, 11). These diamagnetic complexes were characterized by (1) H and (13) C NMR spectroscopy and the molecular structures of compounds 5 a, 6 a, 7, and 10 were well-established by X-ray diffraction analysis. In compounds 5 a, 6 a, and 7, all of the metal centers adopted distorted pentagonal bipyramidal geometries with the NCO donors and two oxygen atoms from the coordinated THF molecules in equatorial positions and the two chlorine atoms in apical positions. Complex 10 is a dimer in which the two equal moieties are linked by two chlorine atoms and two ClLiCl bridges. In each part, the gadolinium atom adopts a distorted pentagonal bipyramidal geometry. Activated with alkylaluminum and borate, the gadolinium and yttrium complexes showed various activities towards the polymerization of isoprene, thereby affording highly cis-1,4-selective polyisoprene, whilst the NCOlutetium complexes were inert under the same conditions.
    Chemistry - An Asian Journal 07/2013; · 4.57 Impact Factor
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    ABSTRACT: High-pressure behaviors of AlN:Mg and AlN:Co nanowires have been investigated by in situ angle dispersive synchrotron X-ray diffraction up to 41.5 GPa and 38.2 GPa, respectively. Their corresponding pressure-induced wurtzite-to-rocksalt phase transitions start at 17.7 GPa and 15.0 GPa and complete at 33.2 GPa and 31.0 GPa, respectively. The phase-transition routes are not affected by the doped ions, while the phase transition pressures are lower than that of pure AlN nanowires. The distinct high-pressure behaviors are ascribed to the doped ions, which reduce the formation energy of cation vacancies and induce Al vacancies defects together with substitution defects, resulting in lattice distortion and affecting structural stability and phase transition pressure.
    Journal of Solid State Chemistry 06/2013; 202:33–37. · 2.04 Impact Factor
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    Xin Tao, Wei Gao, Hang Huo, Ying Mu
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    ABSTRACT: Unchelated scandium(III) trichloride com-plexes, 2 -(ArN=CH)C 6 H 4 Me4 CpScCl 3 Li(THF) 4 (Ar = 2,6-i Pr 2 C 6 H 3 ( 1a ), 2,6-Et 2 C 6 H 3 ( 1b ), 2,6-Me 2 C 6 H 3 ( 1c )), were obtained from the reaction of ScCl 3 (THF) 3 with the li thiu m salt of the corr espo ndi ng liga nd, 2-(A r C 6 H 3 N  CH)C 6 H 4 Me4 CpLi, in THF. After heating at 120° C under vacuum for 30 min, the attached LiCl and THF were removed from complexes 1 to give the che lated scandium (III) dichloride complexes 2-(ArN =CH)C 6 H 4 Me4 CpScCl 2 ([Ar = 2,6-i Pr 2 C 6 H 3 (2a ), 2,6-Et 2 C 6 H 3 ( 2b ), 2,6-Me 2 C 6 H 3 (2c )). Attempts to synthesize dialkyl scandium(III) complexes by the reaction of Sc(CH 2 SiMe 3 ) 3 (THF) 2 with the corresponding free ligands were not successful. The s cand ium(III) trialkyl complex 2 -[Li(THF) 3 (2,6 -i Pr 2 C 6 H 3 )NCH ]C 6 H 4 Me4 CpSc -(CH 2 SiMe 3 ) 3 ( 3 ) was synthesized by a one-pot reaction of ScCl 3 (THF) 3 with 2-(2,6-i Pr 2 C 6 H 3 NCH)C 6 H 4 Me4 CpLi and 3 equiv of Me 3 SiCH 2 Li in THF sequentially. The scandium(III) dialkyl complex 2-(2,6-i Pr 2 C 6 H 3 NCH)C 6 H 4 Me4 CpSc-(CH 2 SiMe 3 ) 2 ( 4 ) was obtained from the reaction of the dichloride complex 2a with 2 equiv of Me 3 SiCH 2 Li in hexane. Complexes1b , c were directly converted to complexes 2b , c without puri fi cation and characterization. All other scandium(III) complexes were characterized by 1 H and 13 C NMR spectroscopy and elemental analyses. The structures of complexes 1a , 2c , 3, and 4 were determined by single-crystal X-ray crystallography, which indicates that the imine N atoms in complexes 1a and 3 do not coordinate to the central scandium atoms. Complexes 2a − c and 4 were found to exhibit moderate catalytic activity for propylene and 1-hexene polymerization upon activation with AlR 3 /Ph 3 CB(C 6 F 5 ) 4 or methylaluminoxane (MAO) and produce atactic polypropylene and isotactic poly(1-hexene). The effects of molecular structures and reaction conditions on the catalytic behavior of these complexes were examined and the possible catalytic mechanism was discussed.
    Organometallics 02/2013; 32:1287. · 4.15 Impact Factor
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    ABSTRACT: The 7-amino-2,4-dimethylquinolinium salts with a variety of anions (Cl−, HCOO−, CH3COO−, PhCOO−, L-HOOCCH(OH)CH(OH)COO−) have been synthesized and characterized. The crystal structures of these salts were determined by single-crystal X-ray diffraction. The structure analysis confirms that the nitrogen atoms in the quinoline rings are protonated in all salts. The two solvates have been obtained and thereby provide a useful complement to cocrystal screening. All the quinolinium salts display interesting three dimensional supramolecular networks. The hydrogen bonding interactions observed in all of the salts are N–HO, O–HO and N–HCl, together with weak C–HO, C–HN, C–HCl hydrogen bonds. The weak C/N–Hπ contacts and π–π stacking interactions involving the quinoline moieties also exist in quinolinium salts. The observed noncovalent interactions become prominent in stabilizing their crystal packing. The 7-amino-2,4-dimethylquinolinium salts show strong luminescence in the solid state and solution in the range 422–534 nm. The solid-state emission spectra of the quinolinium salts are sensitive to the anion species, and highly dependent on the nature of the stacking interactions.
    CrystEngComm 10/2012; 14(21):7275-7286. · 3.88 Impact Factor
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    ABSTRACT: Reactions of N,N,N-tridentate quinolinyl anilido-imine ligands with AlMe(3) afford mononuclear aluminum complexes {κ(3)-[{2-[ArN[double bond, length as m-dash]C(H)]C(6)H(4)}N(8-C(9)H(6)N)]}AlMe(2) (Ar = 2,6-Me(2)C(6)H(3) (1a), 2,6-Et(2)C(6)H(3) (1b), 2,6-(i)Pr(2)C(6)H(3) (1c)) or dinuclear complexes AlMe(3){κ(1)-[{2-[ArN[double bond, length as m-dash]C(H)C(6)H(4)]N(8-C(9)H(6)N)}-κ(2)]AlMe(2) (R = 2,6-Me(2)C(6)H(3) (2a), 2,6-Et(2)C(6)H(3) (2b), 2,6-(i)Pr(2)C(6)H(3) (2c)) depending on the ratios of reactants used. Similar reactions of ZnEt(2) with these ligands give the monoligated ethyl zinc complexes {κ(3)-[{2-[ArN[double bond, length as m-dash]C(H)]C(6)H(4)}N(8-C(9)H(6)N)]}ZnEt (Ar = 2,6-Me(2)C(6)H(3) (3a), 2,6-Et(2)C(6)H(3) (3b), 2,6-(i)Pr(2)C(6)H(3) (3c)) or bisligated complexes {κ(3)-[{2-[ArN[double bond, length as m-dash]C(H)]C(6)H(4)}N(8-C(9)H(6)N)]}Zn{κ(2)-[{2-[ArN[double bond, length as m-dash]C(H)]C(6)H(4)}N(8-C(9)H(6)N)]} (Ar = 2,6-Me(2)C(6)H(3) (4a), 2,6-Et(2)C(6)H(3) (4b), 2,6-(i)Pr(2)C(6)H(3) (4c)). These complexes were well characterized by NMR and the structures of 1a, 2a, 2c, 3b and 4c were confirmed by X-ray diffraction analysis. The aluminum and zinc complexes were tested to initiate lactide polymerization in which the zinc complexes show moderate to high activities in the presence of benzyl alcohol.
    Dalton Transactions 08/2012; 41(37):11454-63. · 3.81 Impact Factor
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    ABSTRACT: Bis(imino)aryl NCN pincer Ni(II) complexes 2,6-(ArN=CH)(2)C(6)H(3)NiBr (1: Ar = 2,6-Me(2)C(6)H(3); 2: Ar = 2,6-Et(2)C(6)H(3); 3: Ar = 2,6-(i)Pr(2)C(6)H(3)) were prepared via the oxidative-addition of Ni(0)(Ph(3)P)(4) with bis(N-aryl)-2-bromoisophthalaldimine. These nickel complexes were characterized by NMR and elemental analyses. Their solid molecular structures were established by X-ray diffraction analyses. The nickel metal centers adopt distorted square planar geometries with the bromine atoms acting as one coordinate ligands. The NCN pincer Fe(II) complexes 2,6-(ArN=CH)(2)C(6)H(3)Fe(μ-Cl)(2)Li(THF)(2) (4: Ar = 2,6-Me(2)C(6)H(3); 5: Ar = 2,6-Et(2)C(6)H(3); 6: Ar = 2,6-(i)Pr(2)C(6)H(3)) were synthesized by lithium salt metathesis reactions of the ligand lithium salts with FeCl(2). X-ray structure analyses of 4 and 5 revealed that the Fe(II) complexes are hetero-dinuclear with the iron atoms in trigonal bipyramidal environments. When activated with MAO, the nickel complexes are active for norbornene vinyl polymerization but are inert for butadiene polymerization. The Fe(II) complexes show moderate activities in butadiene polymerization when activated with alkylaluminium, affording the cis-1,4 enriched polymer.
    Dalton Transactions 07/2012; 41(32):9639-45. · 3.81 Impact Factor
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    ABSTRACT: Syntheses of three benzaldazine compounds 1–3 with the general formula Ar1(CH = N–N = HC)Ar2 (Ar1 = Ar2 = 2-OH-3,5-tBu2C6H2 (1), Ar1 = Ar2 = 2-BrC6H4 (2), Ar1 = ortho-C6H4(NHC6H3-Me2-2,6), Ar2 = C6H4F-2 (3)) are described. All compounds were characterized by elemental analysis, 1H NMR, 13C NMR, IR spectroscopy and single-crystal X-ray crystallography. The different supramolecular structures were obtained through different weak interactions (C − H···O, O − H···N and π···π interactions for 1; C − H···Br and Br···Br interactions for 2; C − H···F and C − H···N interactions for 3). Compound 1 shows solvent-dependent fluorescent properties with blue to green emission on the increasing of the solvent polarity. Compounds 2, 3 show blue photoluminescence in different solvents.
    Comptes Rendus Chimie. 05/2012; 15(5):463–470.
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    ABSTRACT: A number of new half-sandwich zirconium(IV) complexes bearing N,N-dimethylaniline-amido ligands with the general formula Cp*ZrCl(2)[ortho-(RNCH(2))(Me(2)N)C(6)H(4)] [R = 2,6-Me(2)C(6)H(3) (1), 2,6-(i)Pr(2)C(6)H(3) (2), (i)Pr (3), (t)Bu (4)] were synthesized by the reaction of Cp*ZrCl(3) with the corresponding ortho-(Me(2)N)C(6)H(4)CH(2)NRLi. All new zirconium complexes were characterized by (1)H and (13)C NMR, elemental analyses and single crystal X-ray diffraction analysis. The molecular structural analysis reveals that the NMe(2) group does not coordinate to the zirconium atom in all cases. Complexes 1-4 all have a pseudo-tetrahedral coordination environment in their solid state structures and adopt a three-legged piano stool geometry for the zirconium atoms with the amide N atom and the two Cl atoms being the three legs and the Cp* ring being the seat. Variable-temperature (1)H NMR experiments for all complexes 1-4 were performed to investigate the possible intramolecular interaction between the N atom in the NMe(2) group and the central zirconium atom in solution. Upon activation with Al(i)Bu(3) and Ph(3)CB(C(6)F(5))(4), complexes 1-4 all exhibit moderate to good catalytic activity for ethylene polymerization and copolymerization with 1-hexene, producing linear polyethylene or poly(ethylene-co-1-hexene) with moderate molecular weight and reasonable 1-hexene incorporation.
    Dalton Transactions 03/2012; 41(12):3461-7. · 3.81 Impact Factor
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    ABSTRACT: Reactions of CrCl(2)(THF)(2) with N-aryl-9,10-iminophenanthraquinone in CH(2)Cl(2) give the monoimine chromium complexes (Ar)IPQCrCl(2)(THF)(2) (1, Ar = 2,6-Me(2)C(6)H(3); 2, Ar = 2,6-Et(2)C(6)H(3); 3, Ar = 2,6-(i)Pr(2)C(6)H(3)). Molecular structures of 1 and 3 were revealed to be monomeric with the chromium atoms in distorted octahedral geometries. Similar reactions of CrCl(2)(THF)(2) with N,N-bis(arylimino)phenanthrene ligands afford the diimine complexes (Ar1,Ar2)BIPCrCl(μ-Cl)(3)Cr(THF)(Ar1,Ar2)BIP (4, Ar(1) = Ar(2) = 2,6-Me(2)C(6)H(3); 5, Ar(1) = Ar(2) = 2,6-Et(2)C(6)H(3); 6, Ar(1) = Ar(2) = 2,6-(i)Pr(2)C(6)H(3); 7, Ar(1) = 2,6-Me(2)C(6)H(3), Ar(2) = 2,6-(i)Pr(2)C(6)H(3)). The X-ray diffraction analysis shows that 4, 5, and 7 are chlorine-bridged dimers with each chromium atom in a distorted octahedral geometry. Upon activation with MAO, all these complexes exhibit good catalytic activities for isoprene polymerization affording polyisoprene with predominantly a cis-1,4 unit.
    Dalton Transactions 03/2012; 41(9):2755-63. · 3.81 Impact Factor
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    ABSTRACT: A series of new carbonyl rhenium(I) complexes chelated by a substituted 1,10-phenanthroline ligand with the general formula Re(CO)3LCl, where L = 2-(2′-methoxyphenyl)-1,10-phenanthroline (L1), 2-(4′-methoxyphenyl)-1,10-phenanthroline (L2) and 2-(4′-diphenylaminophenyl)-1,10-phenanthroline (L3), have been systemically synthesized. The molecular structure of complex 1 was determined by single crystal X-ray diffraction studies, showing that the complex adopts a distorted octahedral geometry. The electrochemical, photophysical, and thermal properties, as well as the electroluminescent behaviors of three rhenium(I) complexes, were investigated. The solution processable complex 1, 2 or 3 was used as a yellow emitting dopant to fabricate electrophosphorescent devices with a polymerhost. The device based on complex 3 exhibits a maximum current efficiency of 12.2 cd A−1 and a peak brightness in excess of 7300 cd m−2, respectively. Even at a high luminance of 5000 cd cm−2 with current density of 81 mA cm−2, the current efficiency of this device remains as high as 6.4 cd A−1. These results represent the best values reported for electophosphorescent devices based on solution processable rhenium(I) complexes.
    Journal of Materials Chemistry 01/2012; 22(8):3485-3492. · 5.97 Impact Factor
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    ABSTRACT: Two new rhenium(I) complexes chelated by a substituted 2,2′-bipyridine with general formula Re(CO)3LCl, where L = 6 -(2″-methoxyphenyl)-2,2′-bipyridine (L1) and 6 -(4″-diphenylaminophenyl)-2,2′-bipyridine (L2), are synthesized and characterized by IR, NMR, and elemental analysis. Structure of 1 was determined by single-crystal X-ray crystallography, revealing that rhenium is six-coordinate octahedral. The electrochemical, photophysical, and thermal properties of the two rhenium(I) complexes were investigated. Electroluminescent devices were fabricated by doping 1 in polymer blend host of poly(vinylcarbazole) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole using simple solution spin-coating technique. The device exhibits a maximum current efficiency of 2.97 cd A and peak brightness in excess of 2390 cd m.
    Journal of Coordination Chemistry - J COORD CHEM. 01/2012; 65(7):1266-1277.
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    Bo Gao, Qing Su, Wei Gao, Ying Mu
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    ABSTRACT: The two Al atoms in the title compound, [Al(2)(CH(3))(5)(C(23)H(20)NO)], are four-coordinated in a distorted tetra-hedral environment. The coordination of one Al atom includes three methyl-C atoms and the O atom from the ligand, whereas the second Al atom is surrounded by the O atom and one N atom from the ligand as well as by two methyl-C atoms. In the ligand, the dihedral angle between the two phenyl rings in the 9,10-dihydro-phenanthren unit is 20.64 (12)°.
    Acta Crystallographica Section E Structure Reports Online 10/2011; 67(Pt 10):m1374. · 0.35 Impact Factor
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    ABSTRACT: Treatment of the bis(arylimino)acenaphthene (BIAN) ligands with CrCl2(THF)2 in THF affords mononuclear complexes of ArBIANCrCl2(THF)2 (3a, Ar = 2-iPrC6H4; 3b, Ar = 2,6-Me2C6H3) and chlorine-bridging dinuclear complexes ArBIANCrCl(μ-Cl)3Cr(THF)ArBIAN (3c, Ar = 2,6-Et2C6H3; 3d, Ar = 2,6-iPr2C6H3). The molecular structures of 3b–3d were characterized by X-ray diffraction analysis, and all the chromium atoms are in octahedral geometries. Similar reactions of N-(arylimino)acenaphthenones with CrCl2(THF)2 afford the dinuclear chromium complexes with 1,1′-bis(2-aryliminoacenaphthene-1-olate) tetradentate ligands ArBIAOCr2Cl4(THF)2 (4b, Ar = 2,6-Me2C6H3; 4c, Ar = 2,6-Et2C6H3) via a pinacol cross-coupling reaction. Upon activation with MAO, these complexes show moderate-to-high activities in butadiene and isoprene polymerization, affording a cis-1,4-enriched polymer.
    Organometallics 09/2011; 30(20):5480–5486. · 4.15 Impact Factor
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    ABSTRACT: A series of half-sandwich pentamethylcyclopentadienyl chromium(III) complexes bearing a salicylaldiminato ligand, Cp*[2-R(1)-4-R(2)-6-(CH==NR(3))C(6)H(2)O]CrCl [R(1) = (i)Pr (1, 4), (t)Bu (2, 3, 5), Ad (6); R(2) = H (1, 2, 3), (t)Bu (4, 5, 6); R(3) = (i)Pr (1, 2, 5, 6), (t)Bu (3, 4)], were synthesized. All complexes were characterized by elemental analyses and the structures of complexes 1-4 and 6 were determined by X-ray diffraction analysis. These complexes adopt a pseudo-octahedral coordination environment with a three-legged piano stool geometry. Upon activation with a small amount of AlR(3), complexes 1-6 all catalyze the polymerization of ethylene in a quasi living fashion with good to high catalytic activity under mild conditions and produce ultra-high molecular weight polyethylene as spherical particles with a diameter of 1-6 mm. The catalytic activity of these complexes and the molecular weight of the produced polyethylene can be tuned in a broad range by changing the R(1), R(2), and R(3) groups as well as the AlR(3) cocatalyst. It was found that complex 6 with R(1) = Ad, R(2) = (t)Bu, and R(3) = (i)Pr shows the highest catalytic activity and produces polyethylene with the highest molecular weight.
    Dalton Transactions 09/2011; 40(39):10184-94. · 3.81 Impact Factor
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    ABSTRACT: The effects of pressure on the zone-center optical phonon modes of LiBC, which is structurally and electronically similar to the superconductor MgB2, have been investigated by Raman spectroscopy. At ambient pressure, four main lattice modes have been revealed with frequencies at 1173, 831, 552, and 174 cm−1, respectively, while only lines at 1173 and 174 cm−1 correspond to the expected Raman active E2g modes. The longitudinal-optical phonon modes involving the Li sheets which can provide a coupling between neighboring B–C planes are expected to couple with the plasmon mode and are suggested to be related with the appearance of the forbidden lines. With increasing pressures, it is found that LiBC remains stable up to 15.5 GPa. All the observed modes harden and exhibit broadening effects under high pressure, especially for the B–C bond stretching mode (at 1173 cm−1) which shows a nonlinear pressure dependence. It indicates that the broadening may be caused by complex coupling interactions, and the pressure-enhanced coupling should give rise to a strongly anharmonic behavior of these modes.
    physica status solidi (b) 04/2011; 248(5):1158 - 1161. · 1.49 Impact Factor

Publication Stats

119 Citations
179.63 Total Impact Points

Institutions

  • 2002–2014
    • Jilin University
      • • State Key Lab of Superhard Materials
      • • State Key Laboratory of Supramolecular Structure and Materials
      • • Department of Chemistry
      • • State Key Laboratory on Integrated Optoelectronics
      Yung-chi, Jilin Sheng, China
  • 2009
    • Northwestern Polytechnical University
      • Shaanxi Key Laboratory of Friction Welding Technologies
      Xi’an, Liaoning, China
  • 2008
    • Northeast Institute of Geography and Agroecology
      • State Key Laboratory of Polymer Physics and Chemistry
      Beijing, Beijing Shi, China
    • Université de Technologie de Belfort-Montbéliard
      • Laboratoire d’Etudes et de Recherches sur les Matériaux, les Procédés et les Surfaces (LERMPS)
      Belfort, Franche-Comte, France