首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
A nonsymmetric phosphorus ylide and its palladium(II) complex have been synthesized as potential catalytically active compounds. The reaction of 1 equiv nonsymmetric phosphorus ylide, Ph2PCH2PPh2C(H)C(O)PhBr with [Pd(dppe)Cl2], followed by treatment with 2 equiv AgOTf led to [(dppe)Pd(Ph2PCH2PPh2C(H)C(O)PhBr)](OSO2CF3)2, which contains a five-membered P,P chelate ring on one side and a five-membered P,C chelate ring on the other side. The palladium complex was synthesized and investigated by fourier transform infrared spectroscopy (FT-IR), UV–visible, multinuclear (1H, 31P and 19F) nuclear magnetic resonance (NMR), and electrospray ionisation-mass spectroscopic techniques. FT-IR and 31P NMR studies revealed that the phosphorus ylide is coordinated to palladium via the terminal phosphorus (Pc) of the ylide and methene group (CH). Suzuki reactions for varying aryl halides using the cyclopalladated complex as an efficient catalyst were performed. Various aryl halides were coupled with arylboronic acids in DMF, under air, in the presence of 0.001?mol% of the homogeneous catalyst to afford the corresponding cross-coupled products in good to excellent yields.  相似文献   

2.
A new rhodium complex with a nitrogen‐containing bis(phosphine oxide) ligand has been synthesized. The complex was applied to hydroformylation of styrene and displayed high activity and regioselectivity towards the branched aldehyde, which was found to be higher than those of the tertiary bis(phosphine) analogue. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

3.
A new class of easily accessible hemilabile benzimidazolyl phosphine ligands has been developed. The ligand skeleton is prepared from commercially available and inexpensive o-phenylenediamine and 2-bromobenzoic acid. With catalyst loading down to 0.5 mol% palladium, excellent catalytic activity towards the Suzuki-Miyaura coupling of aryl mesylates is still observed. This represents the lowest catalyst loading achieved so far for this reaction in general. X-Ray crystallography shows that new ligand L2 is coordinated with Pd in a κ(2)-P,N fashion.  相似文献   

4.
An efficient host for blue and green electrophosphorescence, 4,6‐bis(diphenylphosphoryl)dibenzofuran ( o‐ DBFDPO ), with the structure of a short‐axis‐substituted dibenzofuran was designed and synthesised. It appears that the greater density of the diphenylphosphine oxide (DPPO) moieties in the short‐axis substitution configuration effectively restrains the intermolecular interactions, because only very weak π–π stacking interactions could be observed, with a centroid‐to‐centroid distance of 3.960 Å. The improved thermal stability of o‐ DBFDPO was corroborated by its very high glass transition temperature (Tg) of 191 °C, which is the result of the symmetric disubstitution structure. Photophysical investigation showed o‐ DBFDPO to be superior to the monosubstituted derivative, with a longer lifetime (1.95 ns) and a higher photoluminescent quantum efficiency (61 %). The lower first singlet state excited level (3.63 eV) of o‐ DBFDPO demonstrates the stronger polarisation effect attributable to the greater number of DPPO moieties. Simultaneously, an extremely high first triplet state excited level (T1) of 3.16 eV is observed, demonstrating the tiny influence of short‐axis substitution on T1. The improved carrier injection ability, which contributed to low driving voltages of blue‐ and green‐emitting phosphorescent organic light‐emitting diodes (PHOLEDs), was further confirmed by Gaussian calculation. Furthermore, the better thermal and morphological properties of o ‐DBFDPO and the matched frontier molecular orbital (FMO) levels in the devices significantly reduced efficiency roll‐offs. Efficient blue and green electrophosphorescence based on the o ‐DBFDPO host was demonstrated.  相似文献   

5.
Russian Chemical Bulletin - The deprotonation of amidine 2-[Ph2P(O)]C6H4NHC(But)=N(2,6-Me2C6H3) (1) with BunLi affords lithium amidinate {2-[Ph2P(O)]C6H4NLiC(But)=N(2,6-Me2C6H3)}2 (2) having a...  相似文献   

6.
Two sets of reaction conditions were established to enable the highly regio- and stereoselective iodohydroxylation of 1,2-allenylic diphenyl phosphine oxides, yielding (E)-2-iodo-3-hydroxy-1-alkenyl diphenyl phosphine oxides with very high stereoselectivity. The scope of this reaction was examined extensively. Notably, studies on the reactivity of optically active substrates indicated that the axial chirality in the starting allenes may be efficiently transferred to the center chirality of the products with no discernible loss of enantiopurity. Due to the importance of phosphine-containing compounds, both as reagents and ligands, this reaction shows potentials in organic synthesis. Investigations using ESI-MS technology on the (18)O-labeled product, which was prepared using (18)O-water as the solvent, indicated that the (18)O atom was bound to phosphorus in the final product and the oxygen atom of the hydroxyl comes from the phosphinyl functionality of the allene reactant. These results provided solid evidence for the formation of a five-membered cyclic intermediate from the neighboring group participation of the diphenylphosphinyl group. To the best of our knowledge, this is the first time that the neighboring group participation of this type of group was observed.  相似文献   

7.
本文通过多步有机反应制备了化合物9-苯基-9′-(4-二苯基氧化膦)苯基-氧杂蒽[diphenyl(4-(9-phenyl-9H-xanthen-9-yl)phenyl)phosphine oxide,DPPO],低温磷光发射光谱测试表明该化合物具有高的三线态能级(2.88eV),它可以作为天蓝色磷光发光材料双(4,6-二氟苯基吡啶-N,C2)吡啶甲酰合铱[bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(Ⅲ),FIrpic,ET=2.62eV]的主体材料.将主体材料DPPO用于蓝色磷光有机发光二极管中,该器件在100cd/m2的亮度下,电流效率和流明效率分别达到30.6cd/A和19.2lm/W,最大外量子效率达到13.6%.  相似文献   

8.
9.
Wen HR  Li CH  Song Y  Zuo JL  Zhang B  You XZ 《Inorganic chemistry》2007,46(17):6837-6839
A neutral nickel complex with the extended tetrathiafulvalene-4,5-dithiolate ligand benzotetrathiafulvalenedithiolate (btdt2-) is synthesized and characterized. From the structural analysis, the neighboring molecules in this complex are stacked in a different way compared to the previously reported single-component metal [Ni(tmdt)2]. The computational studies confirm that the difference in molecular packing results in the variance of conductivity.  相似文献   

10.
A simple and efficient hemilabile-type phosphine ligand, found to be highly effective in Suzuki-Miyaura cross-coupling of aryl chlorides with generally low Pd-catalyst loading (0.05%), was prepared in one step based on an economically attractive approach from commercially available benzamide starting material.  相似文献   

11.
12.
New complex of copper(I) with norbornene-substituted 1-H-2-pyridinylbenzimidazole ligand was synthesized. The compound obtained enters into a metathesis polymerization reaction to give carbochain coppercontaining copolymers exhibiting photo-and electroluminescent properties.  相似文献   

13.
Two new air-stable palladium(II) complexes containing a N4-Schiff-base ligand have been synthesized and investigated as catalysts for the Suzuki-Miyaura reactions. The binuclear complex 2 has proven to be an excellent catalyst for additive-free Suzuki-Miyaura reactions of aryl bromides in neat water at room temperature and aryl chlorides in aqueous-glycerol at 80 °C. Satisfactory to excellent yields of biaryls are obtained with a wide range of substrates with relatively low loading of catalyst.  相似文献   

14.
Synthetic routes to a series of new (salen)CoX (salen = N,N′-bis(salicylidene)-1,2-diaminoalkane; X = Br or pentafluorobenzoate (OBzF5)) species are described. Several of these complexes are active for the copolymerization of propylene oxide (PO) and CO2, yielding regioregular poly(propylene carbonate) (PPC) without the generation of propylene carbonate byproduct. Variation of the salen ligand, as well as the inclusion of organic-based ionic or Lewis basic cocatalysts, has dramatic effects on the resultant (salen) CoX catalytic activity. Highly active (R,R)-(salen- 1 )CoOBzF5 (salen- 1 = N,N′-bis(3,5- di-tert-butylsalicylidene)-1,2-diaminocyclohexane) catalysts with [Ph4P]Cl or [PPN]Y ([PPN] = bis(triphenylphosphine)iminium; Y = Cl or OBzF5) cocatalysts exhibited turnover frequencies up to 720 h1 for rac-PO/CO2 copolymerization, yielding PPC with greater than 90% head-to-tail connectivity. Additionally, the (R,R)-(salen- 1 )CoOBzF5/[PPN]Cl catalyst system demonstrated a krel of 9.7 for the enchainment of (S)- over (R)-PO when the copolymerization was carried out at low temperatures. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5182–5191, 2006  相似文献   

15.
The so-called SPhos phosphine, an extremely active ligand in the amination and Suzuki coupling of sterically-hindered aryl chlorides, has been anchored on different supports such as non-soluble (cross-linked polystyrene) and soluble (non-cross-linked polystyrene and polyethyleneglycol) polymers, as well as high surface silica. SPhos anchored on polyethyleneglycol (PEG-SPhos) showed the best activity for both amination and Suzuki couplings. The PEG-SPhos ligand can be quantitatively recovered from the reaction mixture through precipitation with diethyl ether and recycled in four consecutive runs without loosing activity. 31P NMR spectra of the reused anchored ligand showed that deactivation of the PEG-SPhos ligand comes from the progressive oxidation of the phosphine-to-phosphine oxide.  相似文献   

16.
M Zhang  A Zhao  D Li  H Sun  D Wang  H Guo  Q Gao  Z Gan  W Tao 《The Analyst》2012,137(19):4584-4592
This paper reports the synthesis of a new class of NaLnF(4)-Ag (Ln = Nd, Sm, Eu, Tb, Ho) hybrid nanorice and its application as a surface-enhanced Raman scattering (SERS) substrate in chemical analyses. Rice-shaped NaLnF(4) nanoparticles as templates are prepared by a modified hydrothermal method. Then, the NaLnF(4) nanorice particles are decorated with Ag nanoparticles by magnetron sputtering method to form NaLnF(4)-Ag hybrid nanostructures. The high-density Ag nanogaps on NaLnF(4) can be obtained by the prolonging sputtering times or increasing the sputtering powers. These nanogaps can serve as Raman 'hot spots', leading to dramatic enhancement of the Raman signal. The NaLnF(4)-Ag hybrid nanorice is found to be robust and is an efficient SERS substrate for the vibrational spectroscopic characterization of molecular adsorbates; the Raman enhancement factor of Rhodamine 6G (R6G) absorbed on NaLnF(4)-Ag nanorice is estimated to be about 10(13). Since the produced NaLnF(4)-Ag hybrid nanorice particles are firmly fastened on a silicon wafer, they can serve as universal SERS substrates to detect target analytes. We also evaluate their SERS performances using 4-mercaptopyridine (Mpy), and 4-mercaptobenzoic acid (MBA) molecules, and the detection limit for Mpy and MBA is as low as 10(-12) M and 10(-10) M, respectively, which meets the requirements of the ultratrace detection of analytes. This simple and highly efficient approach to the large-scale synthesis of NaLnF(4)-Ag nanorice with high SERS activity and sensitivity makes it a perfect choice for practical SERS detection applications.  相似文献   

17.
The interaction of 11 Th(IV)-EDTA,-CDTA or-DTPA chelate with glycollic and malic acids has been investigated potentiometrically and the formation of 111 mixed ligand chelates inferred from the potentiometric curves. The hydrolysis and dimerization constants of the binary chelates and the equilibrium constants of the ternary derivatives have been evaluated at 30±1° and 35±1°C and also the thermodynamic functions, viz. F 0, H and S.With 3 Figures  相似文献   

18.
We report the isolation and structural characterization of several monomeric arylpalladium(II) halide complexes containing tri-tert-butyl phosphine, 1-adamantyl-di-tert-butylphosphine, or 2-adamantyl-di-tert-butylphosphine. X-ray diffraction, IR spectroscopy, and theoretical studies indicated that the complexes may be stabilized by agostic interactions. For example, the distance from the closest hydrogen atom to the palladium metal center in the X-ray structure of the 1-adamantyl-phenylpalladium bromide complex 1 was 2.26(3) A. The calculated Pd-H distance of 2.28 A and harmonic vibrational frequencies were in agreement with the measured distance, but Wiberg bond indices indicated only weak M-H-C interactions. Addition of 2-adamantyl-di-tert-butyl phosphine to 1 led to ligand exchange and formation of 2-adamantyl-di-tert-butyl phosphine complex 2. Addition of P(t-Bu)(3) generated free aryl bromide and Pd[P(t-Bu)(3)](2). Reactivity of complex 1 with nucleophiles provided evidence of the intermediacy of these complexes in palladium-catalyzed cross-coupling reactions. Complex 1 reacted with amine and base to form the corresponding arylamine, with tert-butoxide to form the corresponding ether, with boronic acid and fluoride to form the corresponding biaryl, and with styrene to form stilbene. This complex also catalyzed the reaction of bromobenzene with diphenylamine in the presence of base to produce 94% of the amination product in 45 min at room temperature. This rate is comparable to the reaction rate of in situ generated catalysts.  相似文献   

19.
A combination of palladium with ferrocene-based phosphine ligand with a carbon–bromine bond was found to be a good catalyst for the 1,4-addition of arylboronic acids to α,β-unsaturated ketones and the 1,2-addition to aldehydes. Using Pd(dba)2 and (S,Rp)-[1-(2-bromoferrocenyl)ethyl]diphenylphosphine (S,Rp)-1, 3-phenylcyclohexanone was obtained from the reaction of 2-cyclohexen-1-one with phenylboronic acid in the presence of K2CO3 in toluene at room temperature after 3 h in 92% yield with 76% ee. In the 1,2-addition of 4-methylphenylboronic acid to benzaldehyde, 96% of (4-methylphenyl)phenylmethanol was afforded after 24 h, while the enantiomeric excess was only 6%.  相似文献   

20.
Extraction of Eu3+ from 0.1M aqueous perchlorate medium by thenoyltrifluoroacetone (HTTA) and by mixtures of HTTA and tributylphosphate (TBP), HTTA and triphenylphosphine oxide (TPPO), HTTA and trioctylphosphine oxide (TOPO) and HTTA and triphenylarsine oxide (TPAsO) has been studied at various temperatures allowing for the elucidation of the mechanism of extraction in each case and a comparison between the various bases.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号