64 resultados para TITANIUM COMPLEXES BEARING
Resumo:
The synthesis, structures, photophysics, electrochemistry and electrophosphorescent properties of new red phosphorescent cyclometalated iridium(III) isoquinoline complexes, bearing 9-arylcarbazolyl chromophores, are reported. The functional properties of these red phosphors correlate well with the results of density functional theory calculations. The highest occupied molecular orbital levels of these complexes are raised by the integration of a carbazole unit to the iridium isoquinoline core so that the hole-transporting ability is improved in the resulting complexes relative to those with I-phenylisoquinoline ligands. All of the complexes are highly thermally stable and emit an intense red light at room temperature with relatively short lifetimes that are beneficial for highly efficient organic light-emitting diodes (OLEDs).
Resumo:
Synthetic routes to aluminium ethyl complexes supported by chiral tetradentate phenoxyamine (salan-type) ligands [Al(OC6H2(R-6-R-4)CH2)(2){CH3N(C6H10)NCH3}-C2H5] 7: R = H ; 5, 8: R = Cl; 6, 9: R = CH3) are reported. Enantiornerically pure salan ligands 1-3 with (R,R) configurations at their cyclohexane rings afforded the complexes 4, 5, and 6 as mixtures of two diastereoisomers (a and b). Each diastereoisomer a was, as determined by X-ray analysis, monomeric with a five-coordinated aluminium central core in the solid state, adopting a cis-(O,O) and cis-(Me,Me) ligand geometry. From the results of variable-temperature (VT) H-1 NMR in the temperature range of 220-335 K, H-1-H-1 NOESY at 220 K, and diffusion-ordered spectroscopy (DOSY), it is concluded that each diastereoisomer b is also monomeric with a five-coordinated aluminium central core.
Resumo:
The N,N-bidentate ligand 2-{(N-2,6-diisopropylphenyl)iminomethyl)}pyrrole (L-1) and the N,N,P-tridentate ligand 2-{(N-2-diphenylphosphinophenyl)iminomethyl)}pyrrole (L-2) have been prepared. Their reactions with homoleptic yttrium tris(alkyl) compound Y(CH2SiMe3)(3)(THF)(2) have been investigated. Treatment of Y(CH2SiMe3)(3)(THF)(2) with 1 equiv of L-1 generated a THF-solvated bimetallic (pyrrolylaldiminato)yttrium mono(alkyl) complex (1) of central symmetry. In this process, L-1 is deprotonated by metal alkyl and its imino CN group is reduced to C-N by intramolecular alkylation, generating dianionic species that bridge two yttrium alkyl units in a unique eta(5)/eta(1):kappa(1) mode. The pyrrolyl ring behaves as a heterocyclopentadienyl ligand. Reaction of Y(CH2SiMe3)(3)(THF)(2) with 2 equiv of L-1 afforded the monomeric bis(pyrrolylaldiminato)yttrium mono(alkyl) complex (2), selectively. Amination of 2 with 2,6-diisopropylaniline gave the corresponding yttrium amido complex (3). In 3 the pyrrolide ligand is monoanionic and bonds to the yttrium atom in a eta(1):kappa(1) mode. The homoleptic tris(eta(1):kappa(1)-pyrrolylaldiminato)yttrium complex (4) was isolated when the molar ratio of L-1 to Y(CH2SiMe3)(3)(THF)(2) increases to 3:1. Reaction of L-2 with equimolar Y(CH2SiMe3)(3)(THF)(2) afforded an asymmetric binuclear complex (5).
Resumo:
A series of neutral palladium(II) complexes bearing non-symmetric bidentate pyrrole-iminato or salicylaldiminato chelate ligands have been synthesized, and the structure of representative complexes (3a, 4a, and 5a) have been confirmed by X-ray crystallographic analysis. These palladium complexes have been investigated as catalysts for the polymerization of norbornene. Using modified methylaluminoxane (MMAO) as a cocatalyst, these complexes display high activities and produce vinyl-addition polynorborenes. Catalytic activity of up to 8.52 x 10(3) kg/mol(Pd) h has been observed. Wide-angle X-ray diffraction (WAXD) has been used to investigate the polymer microstructure and it has been found that they are non-crystalline.
Resumo:
A series of novel cyclometalated iridium(III) complexes bearing 2,4-diphenylquinoline ligands with fluorinated substituent were prepared and characterized by elemental analysis, NMR and mass spectroscopy. The cyclic voltammetry, absorption, emission and electroluminescent properties of these complexes were systematically investigated. Electrochemical studies showed that the oxidation of the fluorinated complexes occurred at more positive potentials (in the range 0.57-0.69 V) than the unfluorinated complex 1 (0.42 V). In view of the energy level, the lowering of the LUMO by fluorination is significantly less than that of the HOMO. The weak and low energies absorption bands in the range of 300-600 nm are well resolved, likely associated with MLCT and (3)pi-pi* transitions. These complexes show strong orange red emission both in the solution and solid state. The emission maxima of the fluorinated complexes showed blue shift by 9, 24 and 15 nm for 2, 3 and 4, respectively, with respect to the unfluorinated analogous 1. Multilayered organic light-emitting diodes (OLEDs) were fabricated by using the complexes as dopant materials. Significantly higher performance and lower turn-on voltage were achieved using the fluorinated complexes as the emitter than that using the unfluorinated counterpart 1 under the same doping level.
Resumo:
Group 4 complexes containing diphosphinoamide ligands [Ph2PNR](2)MCl2 (3: R = Bu-t, M = Ti; 4: R = Bu-t, M = Zr; 5: R = Ph, M = Ti; 6: R = Ph, M = Zr) were prepared by the reaction Of MCl4 (M = Ti; Zr) with the corresponding lithium phosphinoamides in ether or THF. The structure of [(Ph2PNBu)-Bu-t](2)TiCl2 (3) was determined by X-ray crystallography. The phosphinoamides functioned as eta(2)-coordination ligands in the solid state and the Ti-N bond length suggests it is a simple single bond. In the presence of modified methylaluminoxane or i-Bu3Al/Ph3BC(C6F5)(4), catalytic activity of up to 59.5 kg PE/mol cat h bar was observed.
Resumo:
Poly(styrene-co-acrylamide) (PSAm)-titanium complexes (PSAm . Ti) were prepared and characterized. It is found that the coordination number of acrylamide (Am) to Ti in the complexes is strongly dependent on Am content in PSAm, but not on [Am]/[Ti] ratio in the feed. The infrared and x-ray photoelectron spectra suggest that the polymer-supported complexes possess the structure [GRAPHICS] The catalytic behavior of the complexes in styrene polymerization is described. The catalytic activity is markedly affected by [Al]/[Ti] ratio in the complexes. C-13 NMR, IR, and DSC data indicate that the polystyrene obtained with PSAm . Ti/MAO (MAO = methylaluminoxane) is highly syndiotactic. Use of Et(3)Al and i-Bu(3)Al in place of MAO gives atactic polystyrene. The activities of the various aluminum compounds used as the cocatalysts decrease in the order: MAO > Et(3)Al > i-Bu(3)Al. The polymer-supported complexes show relatively high activity even after the complexes had been exposed to air for 19 h or higher polymerization temperature. (C) 1996 John Wiley & Sons, Inc.
Resumo:
1. 合成了三齿水杨醛稀土配合物,发现配体中含有柔性取代基易生成均配物,而刚性较强的配体生成单烷基配合物。考察了单体浓度、聚合时间等因素对配合物催化丙交酯聚合活性的影响。 2. 以含二苯基膦苯胺的β-二酮单亚胺三齿配体合成了双配体单烷基稀土配合物,空间位阻比较大,因而引发丙交酯聚合的速度比较快。 3. 合成了含甲氧基侧基的芳氧胺四齿双烷基配合物,并合成了芳氧胺与茂(茚)混配的稀土单烷基配合物。首次将它们用于丙交酯的聚合,实验结果发现,双烷基配合物中的双烷基是作为双活性中心起作用的。 4. 合成了含双吡咯烷的稀土烷基配合物,将之应用于丙交酯的聚合,发现位阻大的配合物催化聚合可控性好。并应用双吡咯烷配合物进行了丙交酯和己内酯的共聚合研究。
Resumo:
本论文共合成了两种类型12个稀土金属配合物和一个硅化合物,分别对它们进行了红外、核磁等表征,对其中的9个配合物进行了晶体结构的测定。考察了配体结构和反应条件对所生成的配合物结构的影响,研究了稀土单烷基配合物的反应性,以及稀土双烷基配合物在烷基铝和有机硼盐的共同作用下对丁二烯聚合的催化活性和选择性。主要工作内容和结论如下: (1) 合成了噻吩苯胺配体(HL1),该配体与(Lu,Y)稀土三烷基化合物反应,通过C–H活化和烷基消除反应制备了稀土(Lu,Y)单烷基配合物1和2,配体以少见的C,N模式配位,S原子并不参与配位。配体(HL1)与Sc三烷基化合物反应制备了配体分别以C, N和N, S配位的双配的Sc配合物5。 (2) 通过改变反应时间和溶剂体系,HL1与稀土钇三烷基化合物反应可得到罕见的由稀土烷基化物和胺化物两部分组成的配合物3,它们通过噻吩环上活化的C原子连接在一起。HL1和Lu(CH2SiMe3)2(THF)2LiCH2SiMe3在甲苯和正己烷溶剂中反应可得到以L12Lu(CH2SiMe3)2为阴离子,Li(THF)4为阳离子的离子对4。 (3) 研究配合物1和2的反应性。1和2与过量的PhSiH3反应得到中心金属与Si元素交换的Si化合物。 (4) 合成了噻吩苯基膦胺配体(HL2-4)和苯基膦胺配体(HL5)配体。HL2-5与稀土(Y, Lu和Sc)三烷基化合物反应制备了稀土双烷基配合物6,7,8,9,10,11和12。进一步研究了稀土金属双烷基配合物6–12对丁二烯的催化特性,发现该系列催化剂具有独特的催化性质,能够催化丁二烯高反1,4-聚合(91.3%),得到的聚合物分子量在1到2万之间,分子量分布较窄(1.4–1.6)。 (5) 研究了金属钇(Y),镥(Lu),钪(Sc)三种中心金属对丁二烯聚合活性和反式1,4选择性的影响,发现催化剂对丁二烯聚合活性和反1,4选择性取决于配合物的中心金属原子,其中选择性最高为钪配合物,催化活性最佳的为钇配合物。 (6) 研究了配体HL2-4的N-芳环上的取代基分别为甲基,乙基,异丙基时催化体系对丁二烯反式1,4聚合活性和选择性的影响,发现随着N-芳环上取代基空间位阻的增大,催化剂活性逐渐下降,选择性逐渐增加,但当其取代基为异丙基时,过大的空间位阻导致活性和选择性同时有明显的下降。我们通过改变噻吩基为苯基,比较了相同聚合条件下含噻吩基的稀土双烷基配合物和含苯基的稀土双烷基配合物对丁二烯聚合活性和选择性的影响,发现噻吩环的存在对催化剂的活性和选择性有较大的影响。 (7) 在相同催化剂条件下,研究了不同聚合条件(不同类型的AlR3,不同类型的Borate,Al/Ln比等)对丁二烯反1,4聚合活性和选择性的影响。 我们发现,在AlR3和Borate这两种影响因素中,以烷基铝的类型对催化剂催化活性和选择性的影响最大,而有机硼盐的影响则比较轻微,其中以烷基铝为AliBu3,Borate为[B(C6F5)4][Me2NHPh]时,反1,4选择性为最佳。Al/Ln增大并不能够显著增加催化剂的活性,对选择性的影响也并不明显,相反,随着铝比的增加,聚合过程中的链转移增加,导致分子量下降,对于该系列稀土烷基催化剂,最佳Ln/Al 为10。
Resumo:
The tridentate ligand N-(2-((2,6-diisopropylphenylimino)methyl)phenyl)quinolin-8-amine (HL) was prepared. Treatment of HL with 1 equiv of Ln(CH2SiMe3)(3)(THF)(2) afforded the corresponding rare-earth metal bis(alkyl) complexes LLn(CH2SiMe3)(2)(THF)(n) (Ln = Sc, n = 0 (1); Y, n = 1 (2); Lu, n = 0 (3)) in high yields. Variable-temperature H-1 NMR spectral analysis showed that these complexes were fluxional at room temperature. Complexes 1 and 3 were THF-free, where the metal center adopted a square-pyramidal geometry, while in 2 the metal center generated a distorted octahedral geometry owing to the coordination of a THF molecule.
Resumo:
The first aryldiimine NCN-pincer ligated rare earth metal dichlorides (2,6-(2,6-C6H3R2N=CH)(2)C6H3)LnCl(2)(THF)(2) (Ln = Y, R = Me (1), Et (2), Pr (3); R = Et, Ln = La (4), Nd (5), Gd (6), Sm (7), Eu (8), Tb (9), Dy (10), Ho (11), Yb (12), Lu (13)) were successfully synthesized via transmetalation between 2,6-(2,6-C2H3-R2N=CH)(2)-C6H3Li and LnCl(3)(THF)(1 similar to 3.5). These complexes are isostructural monomers with two coordinating THF molecules, where the pincer ligand coordinates to the central metal ion in a kappa C:kappa N: kappa N' tridentate mode, adopting a meridional geometry.
Resumo:
Five novel vanadium(III) complexes [PhN = C(R-2)CHC(R-1)O]VCl2(THF)(2) (4a: R-1 = Ph, R-2 = CF3; 4b: R-1 =t-Bu, R-2 = CF3; 4c: R-1 = CF3, R-2 = CH3; 4d: R-1 = Ph, R-2 = CH3; 4e: R-1 = Ph, R-2 = H) have been synthesized and characterized. On activation with Et2AlCl, all the complexes, in the presence of ethyl trichloroacetate (ETA) as a promoter, are highly active precatalysts for ethylene polymerization, and produce high molecular weight and linear polymers. Catalyst activities more than 16.8 kg PE/mmolv h bar and weight-average molecular weights higher than 173 kg/ mol were observed under mild conditions.
Resumo:
A series of 2,6-bis(imino)pyridyl iron and cobalt complexes bearing p-substituent [2,6-(ArN=CMe)(2)C5H3N]-MCl2 (Ar=2,6-Me2C6H3, 2,4,6-Me3C6H2, 2,6-Me-2-4-BrC6H2, 2,6-Me-2-4-ClC6H2, 2,4-Me-2-6-BrC6H2, 2,4-Me-(2)-6-ClC6H2, while M=Fe, Co) have been synthesized and investigated as catalysts for ethylene polymerization in the presence of modified methylaluminoxane as a cocatalyst. The electron effect and positions of the substitueni of pyridinebisimine ligands were observed to affect considerably catalyst activity and polymer property.
Resumo:
We report a facile strategy to tether lanthanide complexes to organic-inorganic hybrid titania materials via sol-gel processing by employing chemically modified titanium alkoxide as the precursor where the organic ligand sensitizing the luminescence of lanthanide ions is bonded to titanium.
Resumo:
A series of titanium and zirconium complexes based on aminoiminophosphorane ligands [Ph2P(Nt-Bu)(NR)](2)MCl2 (4, M = Ti, R = Ph; 5, M = Zr, R = Ph; 6, M = Ti, R = SiMe3; 7, M = Zr, R = SiMe3) have been synthesized by the reaction of the ligands with TiCl4 and ZrCl4. The structure of complex 4 has been determined by X-ray crystallography. The observed very weak interaction between Ti and P suggests partial pi-electron delocalization through both Ti and P. The complexes 4-7 are inactive for ethylene polymerization in the presence of modified methylaluminoxane (MMAO) or i-Bu3Al-Ph3CB(C6F5)(4) under atmospheric pressure, and is probably the result of low monomer ethylene concentration and steric congestion around the central metal.