A new rhodium complex with a nitrogen‐containing bis(phosphine oxide) ligand as an efficient catalyst for the hydroformylation of styrene

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.     

Rhodium-tris(3,5-bis(trifluoromethyl)phenyl)phosphine catalyzed hydroformylation of dienes to dialdehydes in supercritical carbon dioxide with high activity

Rhodium-catalyzed hydroformylation of 1,5-hexadiene and 1,7-octadiene to corresponding dialdehydes was investigated in compressed CO₂ and in toluene using different fluorinated phosphine compounds as ligands. A rhodium complex using tris(3,5-bis(trifluoromethyl)phenyl)phosphine is highly effective in compressed CO₂ for double hydroformylation of 1,5-hexadiene, whose TOF value is much larger than those reported so far. It has been shown that this ligand is effective also for the hydroformylation of 1,7-octadiene and scCO₂ is a better solvent than a conventional organic solvent of toluene for the title reaction.     

Design and Synthesis of Isocyanide Ligands for Catalysis: Application to Rh‐Catalyzed Hydrosilylation of Ketones

New isocyanide ligands with meta‐terphenyl backbones were synthesized. 2,6‐Bis[3,5‐bis(trimethylsilyl)phenyl]‐4‐methylphenyl isocyanide exhibited the highest rate acceleration in rhodium‐catalyzed hydrosilylation among other isocyanide and phosphine ligands tested in this study. ¹H NMR spectroscopic studies on the coordination behavior of the new ligands to [Rh(cod)₂]BF₄ indicated that 2,6‐bis[3,5‐bis(trimethylsilyl)phenyl]‐4‐methylphenyl isocyanide exclusively forms the biscoordinated rhodium–isocyanide complex, whereas less sterically demanding isocyanide ligands predominantly form tetracoordinated rhodium–isocyanide complexes. FTIR and ¹³C NMR spectroscopic studies on the hydrosilylation reaction mixture with the rhodium–isocyanide catalyst showed that the major catalytic species responsible for the hydrosilylation activity is the Rh complex coordinated with the isocyanide ligand. DFT calculations of model compounds revealed the higher affinity of isocyanides for rhodium relative to phosphines. The combined effect of high ligand affinity for the rhodium atom and the bulkiness of the ligand, which facilitates the formation of a catalytically active, monoisocyanide–rhodium species, is proposed to account for the catalytic efficiency of the rhodium–bulky isocyanide system in hydrosilylation.     

Rhodium/Phosphine catalysed selective hydroformylation of biorenewable olefins

This work reports rhodium catalyzed selective hydroformylation of natural olefins like eugenol, estragole, anethole, prenol and isoprenol using biphenyl based Buchwald phosphine ligands (S‐Phos ( L ₁ ), t‐Bu XPhos ( L ₂ ), Ru‐Phos ( L ₃ ), Johnphos ( L ₄ ) and DavePhos ( L ₅ ). Ru‐Phos ( L ₃ ) ligand exhibited high impact on the hydroformylation of eugenol providing high selectivity (90%) of linear aldehyde as major product. In addition, internal natural olefins like anethole and prenol provided moderate to high selectivity (65% and 85% respectively) of branched aldehydes as a major products. The various reaction parameters such as influence of ligands, P/Rh ratio, syngas pressure, temperature, time and solvents have been studied. A high activity and selectivity gained on the way to the linear aldehydes it may be due to the bulky, steric cyclohexyl and isopropoxy groups present in L ₃ phosphine ligand. Moreover, this catalytic system was smoothly converting natural olefins into corresponding linear and branched aldehydes with higher selectivity under the mild reaction conditions.     

Two Cd(II) coordination polymers based on tris(p-carboxylphenyl)phosphine oxide accompanied by in situ ligand formation

Two Cd(II) coordination polymers constructed from tris(p-carboxylphenyl)phosphine oxide (H₃TPO), [Cd(HTPO)(1,4-bix)·3H₂O]_n (1) and [Cd₂(HTPO)(HBPO)(H₂O)₂]_n (2) (1,4-bix = 1,4-bis(imidazol-1-ylmethyl)benzene, H₃BPO = bis(4-carboxylphenyl)phosphinic acid), were synthesized and identified by IR, elemental analysis, and single-crystal X-ray diffraction analysis. The 1,4-bix ligand leads to 1 as a ladder-like 1D chain structure. In 2, adjacent Cd₂ units are bridged by HBPO^2– and HTPO^2– ligands to form a 3D structure. The H₃BPO ligand is formed from the in situ reaction of H₃TPO. It is the first example from hydrated Cd(II) salt promoting partial hydrolysis of a phosphine oxide ligand. The thermal behavior and solid-state photoluminescence properties correlated with the corresponding structural features were investigated.     

Syntheses and characterizations of methylpalladium complexes bearing a biphenyl-based bulky phosphine ligand: Weak interactions suggested by NBO and QTAIM analyses

A methylpalladium chloride complex bearing a biphenyl-based bulky phosphine ligand, ^tBu₂P(biphenyl-2-yl) (1), namely [Pd(1)(Me)Cl]₂ (=8), was synthesized by the reaction of (cod)Pd(Me)Cl with 1. A following reaction of 8 with AgOTf gave the corresponding triflate complex, Pd(1)(Me)OTf (=9). These complexes were fully characterized by NMR spectroscopy and structurally characterized by X-ray crystallographic study. In the solid state of 8, biphenyl-based phosphine ligand 1 played a role of monodentate phosphine ligand with a possible weak η¹-coordination from the phenyl ring at 2′-position of 1. On the other hand, phosphine ligand 1 in 9 showed a bidentate coordination mode consist of σ-donation of the phosphine and η²-coordination of the phenyl ring at 1′- and 2′-positions. Natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) calculations also supported the existence of these weak interactions.     

硅胶键合膦的制备及其对铑络合物催化1-辛烯氢甲酰化反应的影响

以硅胶为载体, 采用键合接枝法将2-(二苯膦基)乙基三乙氧基硅烷(DPPES)共价键合于硅胶表面, 制备了性能优良的硅胶键合型膦配体(以SiO₂(PPh₂)表示). 以SiO₂(PPh₂)为配体, Rh(acac)(CO)₂ (acac:乙酰丙酮)为催化前体, 负载铑膦络合物催化剂(SiO₂(PPh₂)/Rh)在1-辛烯氢甲酰化反应中原位生成. 对生成的负载型催化剂和硅胶键合型膦配体进行了傅里叶变换红外(FTIR)光谱表征, 考察了膦/铑摩尔浓度比([P]/[Rh])、温度等因素对铑催化的长链1-辛烯氢甲酰化反应的影响. 结果表明, 膦/铑摩尔浓度比的增加能显著提高反应的成醛选择性, 降低铑的流失. 在[P]/[Rh]=12、363 K、2.0 MPa、1.5 h 的温和反应条件下, 1-辛烯转化率和成醛选择性分别可达98.4%和95.3%, 其催化活性与DPPES或三苯基膦(TPP)作配体时的均相铑催化相近. 催化剂循环4 次后, 反应活性无明显下降, 1-辛烯转化率均在97.0%左右, 经电感耦合等离子体原子发射光谱(ICP-AES)检测,有机相中铑流失低于0.1%.     

Extraction and coordination behavior of diphenyl hydrogen phosphine oxide towards actinides

Extraction behavior of some selected actinides like U(VI), Th(IV), and Am(III) was investigated with three different H-phosphine oxides, viz. diphenyl hydrogen phosphine oxide (DPhPO), dihexyl hydrogen phosphine oxide (DHePO) and diphenyl phosphite (DPP). The H-phosphine oxides exhibited a dual nature towards the extraction of actinides where the ligand not only extracts the metals by cation exchange but also by coordination with the phosphoryl group at lower and higher acidic concentrations, respectively. Among all ligands employed, DPhPO showed highest extraction with actinides with a substituent dependent trend as follows: DPhPO > DHePO > DPP. This trend emphasizes the importance of substituents around the phosphine oxide towards their extraction of actinides. The coordination behavior of DPhPO was studied by investigating its corresponding complexes with Th(NO₃)₄ and UO₂(NO₃)₂. The metal complexes of these actinides were characterized using FT-IR, ¹H and ³¹P NMR spectroscopic techniques. Density Functional Theory (DFT) calculations were also performed to understand the electronic and geometric structure of the ligand and the corresponding metal complexes.     

Selective hydroformylation of various olefins using diphosphinite ligands

Novel diphosphinite ligands are synthesized by the reaction of various derivatives of 1,3‐diols with chlorodiphenylphosphine. The synthesized ligands exhibited considerable impact on hydroformylation of various olefins with excellent regioselectivity toward branched aldehyde. The effect of solvent, temperature, pressure and catalyst loading on the hydroformylation reaction is also described. The synthesized diphosphinite ligands with rhodium precursor works under milder reaction conditions as compared to traditional phosphine and phosphite‐based ligands. Copyright © 2013 John Wiley & Sons, Ltd.     

铑-膦配位催化烯烃氢甲酰化反应研究

本文研究了由Rh2(CO)4CI2分别与两种膦配体4－下丁苯基二苯基膦（1）和4－正辛苯基二苯基磷（2）形成的原位催化剂体系对烯烃氢甲酰化反应的催化性能。对影响反应的各种因素,如P／Rh物质的量比、反应温度、反应压力,不同烯烃等的影响作了探讨。结果表明,配体1、2与Rh2(CO4)CI2形成的原位催化剂体系的催化活性与选择性均高于结构相似的PPh3,在相同的条件下,不同烯烃的氢甲酰化反应活性依直链烯烃＞苯乙烯＞直链内烯＞环己烯的顺序递增。     

Encapsulation of transition metal catalysts by ligand-template directed assembly

Encapsulated transition metal catalysts are presented that are formed by templated self-assembly processes of simple building blocks such as porphyrins and pyridylphosphine and phosphite ligands, using selective metal-ligand interactions. These ligand assemblies coordinate to transition metals, leading to a new class of transition metal catalysts. The assembled catalyst systems were characterized using NMR and UV-vis spectroscopy and were identified under catalytic conditions using high-pressure infrared spectroscopy. Tris-3-pyridylphosphine binds three mesophenyl zinc(II) porphyrin units and consequently forms an assembly with the phosphorus donor atom completely encapsulated. The encapsulated phosphines lead exclusively to monoligated transition metal complexes, and in the rhodium-catalyzed hydroformylation of 1-octene the encapsulation of the catalysts resulted in a 10-fold increase in activity. In addition, the branched aldehyde was formed preferentially (l/b = 0.6), a selectivity that is highly unusual for this substrate, which is attributed to the encapsulation of the transition metal catalysts. An encapsulated rhodium catalyst based on ruthenium(II) porphyrins and tris-meta-pyridyl phosphine resulted in an even larger selectivity for the branched product (l/b = 0.4). These encapsulated catalysts can be prepared easily, and various template ligands and porphyrins, such as tris-3-pyridyl phosphite and ruthenium(II) porphyrins, have been explored, leading to catalysts with different properties.     

OTPPTS对烯烃氢甲酰化反应的影响

 研究了水/有机两相体系中TPPTS(磺化三苯基膦)氧化为OTPPTS(氧化的TPPTS)对Rh/TPPTS催化烯烃氢甲酰化反应的影响. 结果表明,在己烯-1、辛烯-1和十二烯-1氢甲酰化反应中,当n(OTPPTS)/n(TPPTS)＜1时,对催化剂体系性能的影响较小,但当n(OTPPTS)/n(TPPTS)＞1时,将引起催化剂体系的活性、选择性和稳定性下降; 如果保持体系中TPPTS的含量一定,使n(TPPTS)/n(Rh)≥18,当n(OTPPTS)/n(Rh)＝20时,则对催化剂体系性能的影响不明显. 这说明生成的OTPPTS不是铑催化剂的毒物. TPPTS氧化为OTPPTS致使铑催化剂的活性和生成醛的选择性下降, 是由于TPPTS浓度的降低导致n(TPPTS)/n(Rh)值过低,使催化循环中各活性物种的平衡发生变化及铑配合物的稳定性变差所造成的结果.     

Catalytic activity of 1‐methylimidazole‐based phosphine ligands in the palladium‐catalyzed Suzuki coupling reaction

The catalytic activities of three N‐methylimidazole‐based phosphine ligands in the Suzuki coupling reaction were tested using PdCl₂ as the catalyst. The results showed all three phosphine ligands exhibited excellent activity towards the Suzuki reaction, and the catalytic activity decreased with increasing number of imidazole groups. Copyright © 2014 John Wiley & Sons, Ltd.     

Propylene Dimerization by（η^5—C9H7）2 Nickel（Ⅱ）Catalytic System

The catalytic performance of Ni(η^5-Ind)2 complex in the dimerization of propylene was studied in combimation with an organoaluminum co-catalyst,eventually in the presence of a phosphine ligand.The effects of the type of aluminum co-catalyst and its relative amount,the nature of phosphine ligand and P/Ni ratio as well as the reaction temperature were examined.The results indicated that the nickel precatalyst exhibited high productivity for the propylene dimerization together with organoaluminum.It was likely to strongly modify the reactivity in the catalytic sytem when using phosphine ligand as additives,especially at the reaction temperature below 0℃.The catalytic system based on Ni(η^5-Ind)2 complex displaed an extremely high productivity(TOF up to 16900h^-1)and a good regioselectivity to 2,3-dimethylbutenes (2,3-DMB) in dimers(66.4%)under proper reaction parameters.     

Application of chelate phosphine oxide ligand in EuIII complex with mezzo triplet energy level, highly efficient photoluminescent, and electroluminescent performances

The chelate phosphine oxide ligand bis(2-(diphenylphosphino)phenyl) ether oxide (DPEPO) was used as a unit neutral ligand to prepare the complex Eu(TTA)(3)(DPEPO) 1 (TTA = 2-thenoyltrifluoroacetonate). Compound 1 has a photoluminescence (PL) quantum yield of 55.3%, which is more than the twice of the PL quantum yield of Eu(TTA)(3)(TPPO)(2) (TPPO = triphenylphosphine oxide). Investigation indicated that DPEPO in 1 has the mezzo first triplet excited energy level (T(1)) between the first singlet excited energy level (S(1)) and T(1) of TTA, which may support one more additional energy transfer routines from the T(1) energy level of DPEPO to that of TTA, and consequently results in the improvement of energy transfer in the Eu(III) complex. DPEPO forms a complex with a more rigid and compact structure that can improve energy transfer between ligands and the center Eu(III) ion, support the higher saturation level by the coordinating ability of the oxygen atom in the ether moiety, and consequently enhance the PL intensity and efficiency of the corresponding Eu(III) complex. The multilayered electroluminescent (EL) device of 1 used as the red dopant exhibited an impressive brightness of 632 cd m(-2) at 25 V. The device had the excellent voltage-independent spectral stability with an emission peak at 615 nm. To the best of our knowledge, this luminescence is the brightest emission among Eu complexes with phosphine oxide ligands. The maximum external quantum yield (eta(ext)) of 2.89% and the maximum current and power efficiency of 4.58 cd A(-1) and 2.05 lm W(-1) were achieved at a low turn-on voltage of 7 V and current density of 0.021 mA cm(-2). These properties demonstrate that the chelate phosphine oxides ligand DPEPO can not only be favorable to form the rigid and compact complex structure and increase the efficiency of devices, but also reduce the ability of the formation of exciplex. DPEPO shows much better performance compared with the ordinary phosphine oxide ligand triphenylphosphine oxide.     

Recycle and recovery of rhodium complexes with water-soluble and amphiphilic phosphines in ionic liquids for hydroformylation of 1-hexene

A biphasic catalysis system composed of ionic liquid and rhodium complexes with water-soluble or amphiphilic phosphine ligands bearing water-soluble groups of sodium sulfonate have been employed for hydroformylation of 1-hexene. The experimental results show that the activity is almost independent of the hydrotropicity of the phosphine ligands in BMI·BF₄. In this system, the extraction of phosphine species by the organics from the IL phase was quite low but larger than that of rhodium species and showed rather good stability of catalytic activity. A slight decrease in the aldehyde n/i ratio during the catalyst reuse could be recovered, in part, by replenishing certain amount of ligand into the used catalyst system.     

The synthesis of phosphine oxide-linked bis(oxazoline) ligands and their application in asymmetric allylic alkylation

The phosphine oxide-linked bis(oxazoline) ligands were designed and synthesized in two ways. One is the coupling of Grignard reagent derived from 2-(2-bromophenyl)oxazoline with phenylphosphonic dichloride, another route is the condensation of bis(2-formylphenyl)(phenyl)phosphine oxide with chiral amino alcohols followed by NBS oxidation. These new bis(oxazoline) ligands were applied in Pd-catalyzed asymmetric allylic alkylation reactions and good yields and enantioselectivities were obtained with diphenyl substituted ligand (up to 95% ee).     

Synthesis,structural characterization,and olefin polymerization behavior of vanadium(III) complexes bearing bidentate phenoxy‐phosphine ligands

Vanadium(III) complexes bearing phenoxy‐phosphine ligands ( 2a–g ) (2‐R₁‐4‐R₂‐6‐PPh₂‐C₆H₂O)VCl₂(THF)₂ ( 2a : R₁ = R₂ = H; 2b : R₁ = F, R₂ = H; 2c : R₁ = Ph, R₂ = H; 2d : R₁ = tBu, R₂ = H; 2e : R₁ = R₂ = Me; 2f : R₁ = R₂ = tBu; 2g : R₁ = R₂ = CMe₂Ph) were prepared from VCl₃(THF)₃ by treating with 1.0 equiv of the ligand in tetrahydrofuran (THF) in the presence of excess triethylamine (TEA). The reaction of VCl₃(THF)₃ with 2.0 equiv of the ligand in THF in the presence of excess TEA afforded vanadium(III) complexes bearing two phenoxy‐phosphine ligands ( 3c–f ). These complexes were characterized by FTIR and mass spectrum as well as elemental analyses. Structures of 2f and 3c were further confirmed by X‐ray crystallographic analyses. Complexes 2a–g and 3c–f were employed as the catalysts for ethylene polymerization under various reaction conditions. On activation with Et₂AlCl, these complexes exhibited high catalytic activities (up to 41.3 kg PE/mmol_V·h·bar) even at high temperature (70°C), and produced high molecular weight polymer with unimodal molecular weight distributions, indicating the polymerization took place in a single‐site nature. Complexes 3c–f displayed better thermal stability than the corresponding complexes 2a–g under similar conditions. In addition, copolymerizations of ethylene and 1‐hexene with precatalysts 2a–g were also explored in the presence of Et₂AlCl. Catalytic activity, comonomer incorporation, and properties of the resultant polymers can be controlled over a wide range by tuning catalyst structures and reaction parameters.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Catalysis of hydrosilylation XIII. Gas-phase hydrosilylation of acetylene by trichlorosilane on functionalised silica supported rhodium and ruthenium phosphine complexes

Gas-phase hydrosilylation of acetylene by tri-chlorosilane catalyzed in a continuous flow apparatus by rhodium and ruthenium phosphine complexes immobilized on the silica via mercapto, phosphine, amine and nitrile ligands has been studied. GLC analysis of the reaction products showed vinyltrichlorosilane to be accompanied by products of double hydrosilylation of acetylene and the redistribution of trichlorosilane followed by the hydrosilylation and hydrogenative hydrosilylation of acetylene with dichlorosilane. A scheme for this complex competitive–consecutive reaction was proposed. The yield and selectivity of vinyltrichlorosilane can be much improved under special reaction conditions, e.g. rate flow of the particular substrates, temperature, given catalyst and others. Kinetic measurements carried out in the range of 115–140°C allowed us to evaluate the activation energy, E_a, for the vinyltrichlorosilane synthesis, which varied between 20.5 and 27.6 kJ mol^?1 for the selected rhodium and ruthenium supported complexes.     

A novel thermoregulated phosphine ligand used for the Rh-catalyzed hydroformylation of mixed C11~12 olefins in aqueous/organic biphasic system

<正>A novel thermoregulated phosphine ligand Ph_2P(CH_2CH_2O)_nCH_3(n=22) was synthesized and used for the Rh-catalyzed hydroformylation of mixed C_(11-12) olefins in aqueous/organic biphasic system.Under the optimized conditions,pressure =5 MPa (H_2:CO=1:1),phosphine/Rh =13(molar ratio),reaction time =6 h and temperature =130℃,the conversion of C_(11-12) olefins and the yield of aldehyde are 99%and 94%,respectively.The catalyst retained in aqueous phase can be easily separated from the product-containing organic phase by simple phase separation and the catalytic activity remains almost constant after four consecutive cycles.