41 results on '"Xiu-Feng Hou"'
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2. Transition metal catalysed C7 and ortho-selective halogenation of 2-arylbenzo[d]oxazoles
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He-Zhen Cui, Xiu-Feng Hou, Shuang Huang, Xi Hong, Quan Zhou, and Zhiming Li
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010405 organic chemistry ,Aryl ,Organic Chemistry ,Regioselectivity ,chemistry.chemical_element ,Halogenation ,Sonogashira coupling ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,0104 chemical sciences ,Rhodium ,Catalysis ,chemistry.chemical_compound ,chemistry ,Selectivity ,Oxazole - Abstract
2-Arylbenzo[d]oxazole is an important structural motif in pharmaceutical chemistry, while its regioselective halogenation still remains challenging due to the many possible reaction sites on the two aromatic systems. Herein, we report a transition metal catalysed chlorination, bromination and iodination of 2-arylbenzo[d]oxazole with N-halosuccinimide, in which ruthenium-catalysed halogenation occurred on the C7-position and rhodium-catalysed halogenation occurred on the ortho-position. The C7 halogenation was only observed for 5-methyl-2-(p-substituted)arylbenzo[d]oxazoles under rhodium catalysis. Preliminary mechanistic experiments and density functional theory (DFT) calculations suggested that the C7-halogenation catalysed by Ru might have a single-electron-transfer (SET) radical process, while the ortho-selective halogenation catalysed by Rh proceeds probably through a redox-neutral SN2-type mechanism. The different selectivity of Rh catalysed halogenation could be due to the charge difference between benzo[d]oxazolyl and aryl rings. The two kinds of halogenated products were proved to be versatile by constructing aryl and alkynyl groups on the C–X site via Suzuki and Sonogashira cross-coupling reactions. more...
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- 2019
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Catalog
3. Ru(II)‐ PBT NN X N complex bearing functional 2‐(pyridin‐2‐yl)benzo[ d ]thiazole ligand catalyzed α ‐alkylation of nitriles with alcohols
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Yue-Jian Lin, He-Zhen Cui, Shuang Huang, Yong Sun, Xi Hong, Xiu-Feng Hou, and Quan Zhou
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Inorganic Chemistry ,chemistry.chemical_compound ,Bearing (mechanical) ,Ligand ,Chemistry ,law ,General Chemistry ,Alkylation ,Thiazole ,Medicinal chemistry ,law.invention ,Catalysis - Published
- 2020
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4. Iridium(III)- benzoxazolyl and benzothiazolyl phosphine ligands catalyzed versatile alkylation reactions with alcohols and the synthesis of quinolines and indole
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Quan Zhou, He-Zhen Cui, Shuang Huang, Xi Hong, Si-Peng Wu, Yue-Jian Lin, and Xiu-Feng Hou
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Indole test ,010405 organic chemistry ,Ligand ,Organic Chemistry ,chemistry.chemical_element ,Alcohol ,Dihedral angle ,Alkylation ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Medicinal chemistry ,0104 chemical sciences ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Iridium ,Physical and Theoretical Chemistry ,Phosphine - Abstract
A series of benzoxazolyl and benzothiazolyl phosphine ligands 4a-4g were synthesized and characterized, which prepared from commercially available 2-aminophenol/2-aminobenzenethiol and 2-bromobenzaldehyde via cyclization and phosphination. The representative ligands 4c and 4e were determined by single-crystal X-ray diffraction. The corresponding iridium complexes could be generated in situ when [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) encountered ligands. The molecular structures of complexes 5c and 5e were crystallographically characterized. The dihedral angles of N (1)-C (1)-C (8)-C (9) showed an increasing twist compared with the corresponding ligand. The iridium (III) catalysts were screened, [Cp*IrCl2]2/4a proved to be the optimal catalyst, which exhibited efficient catalytic activity toward versatile alkylations including ketones, secondary alcohols and amines with primary alcohols. Additionally, the synthesis of quinolines from ketones with 2-aminobenzyl alcohol by intermolecular cyclization and indole from 2-(2-aminophenyl)ethanol by intramolecular cyclization were achieved under the optimized conditions. more...
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- 2018
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5. The Construction of C–N, C–O, and C(sp2)–C(sp3) Bonds from Fluorine-Substituted 2-Aryl Benzazoles for Direct Synthesis of N-, O-, C-Functionalized 2-Aryl Benzazole Derivatives
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Quan Zhou, Xi Hong, He-Zhen Cui, Ying Yi, Shuang Huang, and Xiu-Feng Hou
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010405 organic chemistry ,Aryl ,Organic Chemistry ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Nitrogen ,Medicinal chemistry ,Oxygen ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Nucleophile ,Nucleophilic aromatic substitution ,Atom economy ,Fluorine ,Palladium catalyst - Abstract
Herein, a general and practical route to 2-(2-aminophenyl)- and 2-(2-alkoxyphenyl)-substituted benzazoles by nucleophilic aromatic substitution (SNAr) is described. Upon treatment with Cs2CO3, the formation of C–N, C–O bonds occur between fluorine-substituted 2-aryl benzazoles and a diverse range of nitrogen, oxygen nucleophiles to provide the targets in good to excellent yields. Commercially available nucleophiles and high atom economy are notable features of the protocol. Meanwhile, the construction of C(sp2)–C(sp3) bond was also furnished in the presence of palladium catalyst. more...
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- 2018
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6. Mesocellular silica foams supported size-controlled Pd nanoparticles for racemic and asymmetric iodomethyl dihydrobenzofuran synthesis
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Hui Zhang, Xi Hong, Bing Zhan, He-Zhen Cui, Aikebaier Reheman, Zhan-Ming Zhang, Xiu-Feng Hou, and Junliang Zhang
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Chemistry ,Substrate (chemistry) ,02 engineering and technology ,General Chemistry ,Mesoporous silica ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Heterogeneous catalysis ,01 natural sciences ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Chemical engineering ,Mechanics of Materials ,Molecule ,General Materials Science ,0210 nano-technology ,Mesoporous material ,Chirality (chemistry) ,Phosphine - Abstract
Supported metal nanoparticles (NPs) catalysts in constructing benzene-fused cyclic framework with chirality is very challenging. Dihydrobenzofuran and its derivatives are significant heterocyclic units in biologically molecules. Herein, size-controlled Pd NPs fixed on mesoporous silica (Pd/MS-xT) SBA-15, FDU-12 and mesocellular silica foams (MCFs) were utilized to synthesize racemic and asymmetric iodomethyl dihydrobenzofuran for the first time. The size of Pd NPs was regulated by increasing NaBH4 reduction treatments times (-xT) and enlarging supports pore. Based on large mesopore of MCF-3, supported catalyst 3%Pd/MCF-3-4T possessed larger Pd size gave the excellent performance at 92% racemic yield. Under chiral phosphine modifier N–Me-Xu3, we implemented more deserving asymmetric reaction over 3%Pd/MCF-3-1T with smaller Pd NPs. TGA for organic surface coverage demonstrated that the substrate preferred larger Pd NPs, N–Me-Xu3 capped more easily on smaller ones. Besides, effects of reaction medium and N–Me-Xu3 additive quantity further revealed the coordination of chiral modifier on Pd/MCF-3 was the determinant. For broader visions, the performance dependence based on surface properties of heterogeneous catalyst would play crucial contributions towards construction of complexed organic molecules. more...
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- 2021
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7. N-Heterocyclic Carbene (NHC)-Catalyzed One-Pot Aerobic Oxidative Synthesis of 2-Substituted Benzo[d]oxazoles, Benzo[d]thiazoles and 1,2-Disubstituted Benzo[d]imidazoles
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Xi Hong, Ming Ma, Jing-Fan Zhang, He-Zhen Cui, Shuang Huang, Shu Liu, Xiu-Feng Hou, and Quan Zhou
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chemistry.chemical_classification ,010405 organic chemistry ,Organic Chemistry ,Salt (chemistry) ,Oxidative phosphorylation ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Organocatalysis ,Efficient catalyst ,Carbene - Abstract
N-Heterocyclic carbene (NHC), generated in situ from easily available N-heterocyclic imidazolium salt with air as terminal oxidant, has successfully been utilized as a cheap and efficient catalyst for one-pot aerobic oxidative synthesis of 2-arylbenzo[d]oxazoles, 2-substituted benzo[d]thiazoles, and 1,2-disubstituted benzo[d]imidazoles. more...
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- 2017
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8. Recyclable Silica-Supported Iridium Catalysts for Selective Reductive Transformation of Quinolines with Formic Acid in Water
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Xi Hong, Xiu-Feng Hou, Rui Zhong, Jing-Fan Zhang, He-Zhen Cui, Shuang Huang, and Quan Zhou
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Formic acid ,Organic Chemistry ,Quinoline ,chemistry.chemical_element ,02 engineering and technology ,Benzoxazole ,Mesoporous silica ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Transfer hydrogenation ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Organic chemistry ,Reactivity (chemistry) ,Iridium ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
Mesoporous silica (SBA-15)-supported iridium catalysts are prepared by grafting of the newly developed cyclometalated iridium 2-aryl benzoxazole complexes with 3-(triethoxysilyl)-propyl-isocyanate (TEPIC) as a linker. The supported catalysts are characterized by solid-state NMR spectroscopy, small-angle X-ray scattering (SAXS), nitrogen physisorption, FTIR spectroscopy, and electron microscopy analysis, which indicate that the coordination environment of the iridium center as well as the two-dimensional hexagonal pore structure of SBA-15 is maintained after the immobilization. These supported catalysts have been successfully applied to the selective transfer hydrogenation of quinoline derivatives to 1,2,3,4-tetrahydroquinolines (THQs) with formic acid in pure water. Moreover, by simply adapting the amount of formic acid used, N-formyltetrahydroquinolines (FTHQs) could be selectively synthesized from quinolines in two-step, one-pot transfer hydrogenation/N-formylation reactions with these supported catalysts. Notably, these supported catalysts showed better catalytic reactivity than their homogeneous analogs, and they can be easily reused 12 times in the transformation of quinoline to N-formyltetrahydroquinoline (FTHQ) without significant loss of activity. more...
- Published
- 2017
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9. Transformation of a Cp*-iridium carbene catalyst in water oxidation using Oxone as primary oxidant
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Jing-Fan Zhang, Shuang Huang, Xiu-Feng Hou, Hui Cao, Xi Hong, and Quan Zhou
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010405 organic chemistry ,Ligand ,Process Chemistry and Technology ,Inorganic chemistry ,chemistry.chemical_element ,Nuclear magnetic resonance spectroscopy ,Potassium peroxymonosulfate ,010402 general chemistry ,01 natural sciences ,Chloride ,Catalysis ,0104 chemical sciences ,Acetic acid ,chemistry.chemical_compound ,chemistry ,medicine ,Water splitting ,Iridium ,Physical and Theoretical Chemistry ,medicine.drug - Abstract
Fundamental understanding of the real catalytic species in water oxidation is a major knowledge gap that must be overcome in order to develop artificial water splitting systems and produce chemical fuels from solar energy. In an effort to analyze the transformation and catalytic resting state of [Cp*Ir(pmNHC)Cl]Cl [pmNHC = 1-(2-pyrimidyl)-3- n -butylimidazol-2-ylidene, Cp* = pentamethylcyclopentadienyl] in water oxidation using potassium peroxymonosulfate (Oxone) as primary oxidant, we found the precatalyst evolved into blue solution when a small amount of Oxone was added while further oxidation yield purple solution. These species have been proven to be homogeneous and they remain active in water oxidation. 1 H NMR profiles and MALDI-MS data suggested a rapid oxidation of the Cp* ligand to acetone, formic and acetic acid. 1 H NMR, TEM-EDX as well as MALDI-MS data indicated a continuous degradation of pyrimidyl, butyl and NHC groups. MALDI-MS, XANES and 17 O NMR spectroscopy data of the blue species are most consistent with an iridium(III) compound with two waters, one dioxygen and pmNHC group. The catalytic resting purple species probably consists of an iridium(III) complex with three waters, one chloride and one bicarbonate ligand. Besides, the presence of a small amount of iridium aqua ion oligomers was observed in the purple species. The formation of polymers and nanoparticles is likely to be inhibited by the acid environment. more...
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- 2017
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10. N-Methylation of ortho-substituted aromatic amines with methanol catalyzed by 2-arylbenzo[d]oxazole NHC-Ir(iii) complexes
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Xiu-Feng Hou, He-Zhen Cui, Quan Zhou, Shuang Huang, Xi Hong, and Yue-Jian Lin
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Benzimidazole ,010405 organic chemistry ,Ligand ,Substituent ,Benzoxazole ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,0104 chemical sciences ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Carbene ,Methyl group ,Oxazole - Abstract
Seven new chelated cyclometalated Ir complexes of ABON,P, ABON,O, and ABON,C(carbene) based on a rigid and tunable 2-arylbenzo[d]oxazole backbone have been prepared for the N-methylation of amines. Among these three coordinated modes, ABON,C(carbene)-chelated iridium-based catalysts exhibited good performance in the monomethylation of aromatic amines with methanol (MeOH) as the green methylation reagent. The steric-modified synthesis of ABON,C(carbene) complexes was described. The most active ABON,C(carbene) complex with marginal steric hindrance as a catalyst was obtained from the benzoxazole ring without a substituent and methyl group of the benzimidazole ring on the N-heterocyclic carbene (NHC) ligand. A variety of amines including para- and meta-substituted aromatic amines, as well as heterocyclic amines, were formulated as suitable substrates. Importantly, this catalyst considerably promoted the yield of the N-methylation of ortho-substituted aromatic amines. Controlled kinetic experiments and deuterium-labeling reactions of these ortho-substituted amines were conducted under optimized conditions. On the basis of the experimental results, a plausible mechanism was proposed. more...
- Published
- 2019
11. Ortho-substitution groups promoted photo-induced E (trans) → Z (cis) isomerization
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Yong Sun, Xi Hong, He-Zhen Cui, Quan Zhou, Bing Zhan, Aikebaier Reheman, and Xiu-Feng Hou
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010405 organic chemistry ,Chemistry ,Aryl ,Organic Chemistry ,Conjugated system ,010402 general chemistry ,Fluorescent quenching ,01 natural sciences ,Biochemistry ,Fluorescence ,Medicinal chemistry ,Cycloaddition ,0104 chemical sciences ,chemistry.chemical_compound ,Drug Discovery ,Controlled experiment ,Isomerization - Abstract
The past decades have witnessed the fast growth of ortho-directing group assisted in C H activation and olefination. Herein we addressed these olefination products’ photo-induced E → Z isomerization in term of various ortho-substitution groups. Initially, we discovered ortho benzoxazolyl aryl acrylates effectively undertook E → Z isomerization (up to 88% yields) under 365 nm direct irradiation. Furthermore, scoping other five directing groups in C H activation and olefination revealed that acetylamino group also present to be good ortho-substituted groups that enhancing E → Z isomerization. Controlled experiment shows the substitution position is vital for photo-induced isomerization or [2 + 2] cycloaddition. Lastly, prevalent interesting fluorescent quenching/change phenomenon were always in accompany with the isomerization. X-ray single crystallography disclose the isomerization process undertook significant conjugated distortion of the aryl acrylates fragment, we proposed such change could contribute to fluorescent and absorbent decrease. more...
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- 2020
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12. Surface-driven imidazolium-coated periodic mesoporous organosilicas for selective synthesis of electron-deficient 2-arylbenzo[d]oxazoles
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Xi Hong, Shuang Huang, He-Zhen Cui, Quan Zhou, Bing Zhan, and Xiu-Feng Hou
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Schiff base ,Chemistry ,Substrate (chemistry) ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Heterogeneous catalysis ,01 natural sciences ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Mesoporous organosilica ,Adsorption ,Mechanics of Materials ,Selective adsorption ,General Materials Science ,0210 nano-technology ,Selectivity - Abstract
Selective synthesis driven by appropriate support properties of heterogeneous catalysts is promising, but long-term process to explore. In this work, we prepared and confirmed series of hydrophobic ethyl bridges modulated periodic mesoporous organosilica fixed with 1-methyl-3-(3-(trimethoxysilyl)propyl)-1H-imidazole-3-iumiodide (MBIm-PMO-x). The contents of hydrophobic ethyl bridges (x) were 0, 5, 15, 25, 35 mol%. These materials were applied for synthesizing heterocyclic compound 2-arylbenzoxazoles with arylaldehydes and 2-aminophenol. Among them, MBIm-PMO-15, hydrophobic ethyl bridge was 15 mol%, dramatically enhanced the yields of synthesizing electron-deficient 2-arylbenzoxazoles. For substrates with different electronic properties, we found MBIm-PMO-15 exhibited the reversed catalytic activity in relation to corresponding homogeneous MBIm. Further research, FT-IR adsorption and UV–vis detection tests demonstrated this kind heterogeneous catalyst surface prefers adsorbing electron-deficient intermediates Schiff base to electron-rich ones. It is the specific adsorption motivate MBIm-PMO-15 highly selectivity towards electron-deficient 2-arylbenzoxazoles. In a broader vision, surface driven selective adsorption of heterogeneous catalyst for substrate could act as an alternative strategy to get special target products. more...
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- 2020
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13. Simultaneous determination of 22 phthalate esters in polystyrene food-contact materials by ultra-performance convergence chromatography with tandem mass spectrometry
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He-Zhen Cui, Minli Yang, Xiu-Feng Hou, Shu Liu, Ying-Li Fan, and Ming Ma
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Detection limit ,Diisononyl phthalate ,Chromatography ,010401 analytical chemistry ,Phthalate ,Filtration and Separation ,02 engineering and technology ,Diisobutyl phthalate ,021001 nanoscience & nanotechnology ,Diisodecyl phthalate ,Mass spectrometry ,Tandem mass spectrometry ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,chemistry.chemical_compound ,chemistry ,0210 nano-technology ,Dimethyl phthalate - Abstract
A method for the determination of 22 phthalate esters in polystyrene food-contact materials has been established using ultraperformance convergence chromatography with tandem mass spectrometry. In this method, 22 phthalate esters were analyzed in more...
- Published
- 2018
14. Activity and Recyclability Improvement Through Adjusting the Tethering Strategy for Pd-Catalyzed Suzuki–Miyaura Coupling Reaction of Aryl Chlorides
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Jing-Fan Zhang, Mingda Wang, Xu-Qing Guo, Shu Liu, Quan Zhou, Hui Cao, Yuan-Long Li, and Xiu-Feng Hou
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Aryl ,chemistry.chemical_element ,General Chemistry ,Catalysis ,Coupling reaction ,chemistry.chemical_compound ,chemistry ,Moiety ,Organic chemistry ,Mesoporous material ,Carbene ,Organometallic chemistry ,Palladium - Abstract
Four mesoporous SBA-15-immobilized N-heterocyclic carbene (NHC) palladium catalysts with different nitrogen ligands were synthesized. The activity and recyclability of the catalysts were investigated in Suzuki–Miyaura cross-coupling reaction of typical aryl chlorides and arylboronic acids. Bulky NHC moiety was essential for efficiency, while tethering of nitrogen ligands on both support and NHC group could dramatically improve recyclability of the catalysts. The strategy offers an alternative strategy for designing highly efficient and recyclable immobilized catalysts. Mesoporous silica-immobilized palladium catalysts with the bulky N-heterocyclic carbene and tethered “throw-away”nitrogen ligands were found to be highly efficient and recyclable for Suzuki–Miyaura coupling reaction of inactive aryl chlorides. more...
- Published
- 2015
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15. Imino-N-Heterocyclic Carbene Palladium(II) Complex-Catalyzed Direct Arylation of Electron-Deficient Fluoroarenes with 'On and Off' Chelating Effect Assistance
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Xiu-Feng Hou, Xu-Qing Guo, Xiao-Han Zhu, Ya-Nong Wang, Quan Zhou, and Zhiming Li
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Aryl ,Organic Chemistry ,Halide ,chemistry.chemical_element ,Nitrogen ,Medicinal chemistry ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Organic chemistry ,Chelation ,Physical and Theoretical Chemistry ,Selectivity ,Carbene ,Palladium - Abstract
An imino-N-heterocyclic carbene palladium(II) complex with a bulky substituted group on the imino nitrogen was used to catalyze the direct arylation of electron-deficient fluoroarenes with aryl halides. A series of electron-poor substrates and aryl bromides could be coupled in good to excellent yields with satisfactory position selectivity (20 examples, up to 93%). These arylations could proceed at a relatively low temperature (80 °C, 20 examples, up to 95%) with mono-N-protected amino acid assistance. Some of them even gained higher yields than those at high temperature (110 °C). Otherwise, some aryl iodides can forge cross-coupling products in yields of nearly 30% under the optimized conditions. The rate profiles for arylation of electron-poor arenes were measured in the presence of the imino-N-heterocyclic carbene palladium(II) complex or Pd(OAc)2 as the catalyst, which showed that the former could keep catalytic activity for a longer time. Computational studies indicated that the imino nitrogen in the... more...
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- 2015
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16. Efficient and versatile transfer hydrogenation catalysts: Iridium (III) and ruthenium (II) complexes with 4-acetylbenzyl-N-heterocyclic carbenes
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Chen-Xi Wang, Xiu-Feng Hou, Xiao-Han Zhu, Li-Hua Cai, Xu-Qing Guo, and Ya-Nong Wang
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Chemistry ,Process Chemistry and Technology ,Cationic polymerization ,chemistry.chemical_element ,Noyori asymmetric hydrogenation ,Alkylation ,Transfer hydrogenation ,Catalysis ,Ruthenium ,chemistry.chemical_compound ,Polymer chemistry ,Organic chemistry ,Iridium ,Physical and Theoretical Chemistry ,Carbene - Abstract
New 4-acetylbenzyl-N-heterocyclic carbene ligands (1–4) have been used to synthesize iridium complexes 6–9 and ruthenium complex 10. All complexes were characterized by FT-IR, 1H and 13C NMR spectroscopy, elemental analysis, and in the case of 6, by X-ray diffraction studies. The catalytic performance of these iridium and ruthenium complexes for transfer hydrogenation of ketones and imines and N-alkylation of amines with primary alcohols were tested in a range of substrates, and showed high catalytic activity with 1 mol% catalytic loading. The neutral complex 8 with two acetyl groups also showed good catalytic efficiency under lower catalyst loading (0.01 mol%), with the maximum TON of 8000, while on the other hand, the cationic complex 9 with PF6− as counteranion showed good to excellent catalytic activity toward the N-alkylation of amines in a wide scope of substrates. We also found out that the Ir complex 6′ was formed through the intramolecular C H activition of 6 under the transfer hydrogenation conditions. more...
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- 2014
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17. A versatile designed synthesis of magnetically separable nano-catalysts with well-defined core–shell nanostructures
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Jinxiu Wang, Wei Li, Jianping Yang, Dongyuan Zhao, Yonghui Deng, Zhenkun Sun, Xiu-Feng Hou, and Serge Kaliaguine
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Nanostructure ,Materials science ,Renewable Energy, Sustainability and the Environment ,Shell (structure) ,Nanoparticle ,Nanotechnology ,General Chemistry ,Mesoporous silica ,Catalysis ,chemistry.chemical_compound ,Colloid ,chemistry ,Nano ,General Materials Science ,Magnetite - Abstract
Multifunctional microspheres with core–shell structures consisting of a core of nonporous carbon-protected magnetite particles, a transition layer of active Pd (or Pt) nanoparticles, and an outer shell of ordered mesoporous silica with perpendicularly aligned pore channels were synthesized based on colloid and interface chemistry. As a magnetically separable catalyst system, such microspheres hold a good potential in liquid phase catalysis. more...
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- 2014
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18. An Efficient and Recyclable Catalyst for N-Alkylation of Amines and β-Alkylation of Secondary Alcohols with Primary Alcohols: SBA-15 Supported N-Heterocyclic Carbene Iridium Complex
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Zi-Wei Gao, Xiu-Feng Hou, Dong Wang, Xu-Qing Guo, Li-Hua Cai, Rui Zhong, Xiao-Han Zhu, Ya-Nong Wang, and Chen-Xi Wang
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chemistry.chemical_compound ,Aniline ,chemistry ,Benzyl alcohol ,chemistry.chemical_element ,Moiety ,Organic chemistry ,General Chemistry ,Iridium ,Mesoporous silica ,Alkylation ,Carbene ,Catalysis - Abstract
A mesoporous silica (SBA-15)-supported pyrimidine-substituted N-heterocyclic carbene iridium complex was prepared and used as a catalyst for both environmentally friendly N-alkylation of amines and β-alkylation of secondary alcohols with primary alcohols. The structure of the supported iridium catalyst was characterized by Fourier transform infrared (FT-IR), 13C and 29Si solid-state nuclear magnetic resonance (NMR), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), iridium K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopic analyses which demonstrated that the coordination environment of the iridium centre and the 3-dimensional-hexagonal pore structure of SBA-15 were retained after the immobilization. The catalyst was found to be highly efficient for both kinds of reaction on a wide range of substrates under mild conditions. Moreover, the supported iridium catalyst was obviously superior to the unsupported one in the N-alkylation of aniline and β-alkylation of 1-phenylethanol with benzyl alcohol as substrate, which indicated that not only the iridium complex moiety but also the support material contributed to the catalytic activity of the supported iridium catalyst in these reactions. The supported iridium catalyst can be easily recycled by simple washing without chemical treatment, and exhibited excellent recycling performance without notable decrease in catalytic efficiency even after twelve test cycles for N-alkylation of aniline with benzyl alcohol, nine cycles for N-alkylation of different amines with different alcohols, and eight cycles for β-alkylation of 1-phenylethanol with benzyl alcohol, respectively. more...
- Published
- 2013
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19. Synthesis of o-Alkenylated 2-Arylbenzoxazoles via Rh-Catalyzed Oxidative Olefination of 2-Arylbenzoxazoles: Scope Investigation, Structural Features, and Mechanism Studies
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Jing-Fan Zhang, Quan Zhou, Rui Zhong, Xiu-Feng Hou, and Hui Cao
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010405 organic chemistry ,Stereochemistry ,Chemical shift ,Organic Chemistry ,Heteroatom ,Substituent ,Regioselectivity ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,Electrophile ,Functional group ,Molecule - Abstract
2-Arylbenzazoles are promising molecules for potential applications in medicine and material areas. Efficient protocols for direct regioselective functionalization of 2-arylbenzoxazoles are in high demand. Herein, we disclose a general method for selective ortho-olefination of 2-arylbenzo[d]oxazoles with alkenes enabled by versatile Cp*Rh(III) in high yields. This protocol features broad functional group tolerance and high regioselectivity. Intermolecular competition studies and kinetic isotope effect experiments imply that the oxidative olefination process occurs via an electrophilic C-H activation pathway. The molecular structure of the m-fluoro-substituted olefination product confirms regioselective C-H activation/olefination at the more hindered site in cases where the meta F atom or heteroatom substituent existed. Apparent torsion angles were observed in the structures of mono- and bis-olefination products, which resulted in distinct different chemical shifts of olefinic protons. Additionally, two gram-scale reactions and further transformation experiments demonstrate that this method is practical for synthesis of ortho-alkenylated 2-arylbenzoxazole derivatives. more...
- Published
- 2016
20. N-Heterocyclic Carbene Palladium Catalyzed Regioselective Oxidative Trifluoroacetoxylation of Unactivated Methylene sp3 C–H Bonds in Linear Alkyl Esters
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Xiu-Feng Hou, Inigo Göttker-Schnetmann, and Ya-Nong Wang
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inorganic chemicals ,chemistry.chemical_classification ,Organic Chemistry ,Regioselectivity ,chemistry.chemical_element ,Medicinal chemistry ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Trifluoroacetic acid ,Organic chemistry ,Physical and Theoretical Chemistry ,Methylene ,Selectivity ,Carbene ,Alkyl ,Palladium - Abstract
Several N-heterocyclic carbene palladium catalyzed oxidation of nonactivated sp3 C–H bonds in linear primary and secondary trifluoroacetic acid esters have been developed. A high selectivity for th... more...
- Published
- 2011
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21. Preparation of Mononuclear, Homodinuclear, and Heterotrinuclear Complexes by Salicylaldiminato-Functionalized Imidazolium Salt: Approach to Multifunctional Catalysts
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Xiu-Feng Hou, Ya-Nong Wang, Xu-Qing Guo, Rui Zhong, and Zhenxia Chen
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chemistry.chemical_classification ,Schiff base ,Organic Chemistry ,Salt (chemistry) ,Halogenation ,General Chemistry ,Transfer hydrogenation ,Catalysis ,Metal ,chemistry.chemical_compound ,chemistry ,Transition metal ,visual_art ,Polymer chemistry ,visual_art.visual_art_medium ,Moiety ,Organic chemistry - Abstract
A salicylaldiminato imidazolium salt that bears both a Schiff base and imidazolium salt moiety was used to synthesize heterometallic compounds that could serve as multifunctional catalysts in certain reactions. The successful preparation of seven mononuclear compounds with a variety of transition metals (Pd, Ir, Ru, Zn, Ni) illustrated the high versatility of this class of ligands, which is crucial for the design of catalysts. Synthesis of homodinuclear compounds and heterotrinuclear compounds provided practical methods to connect multiple metal fragments through these ligands. The heterotrinuclear complex (Ni/Ir) was employed as a catalyst in the reaction of dehalogenation/transfer hydrogenation of halo-acetophenones. The preliminary catalytic study showed that this heterometallic species is more active than a combination of the corresponding monometallic species. more...
- Published
- 2011
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22. Effect of counterions and central cores of tripodal imidazolium salts on palladium-catalyzed Suzuki–Miyaura cross-coupling reactions
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Xu-Qing Guo, Xiu-Feng Hou, Rui Zhong, and Ya-Nong Wang
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chemistry.chemical_classification ,Aryl ,Organic Chemistry ,Salt (chemistry) ,Halide ,chemistry.chemical_element ,Biochemistry ,Coupling reaction ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,Counterion ,Benzene ,Palladium - Abstract
Seven tripodal imidazolium salts were synthesized and used as catalyst precursors in cross-coupling reactions of aryl halides with arylboronic acids. Effect of counterions and central cores of seven tripodal imidazolium salts was investigated. The tripodal imidazolium salt anchored to benzene with anion PF 6 − was found most effective with Pd(OAc) 2 for the cross-coupling of aryl bromides with arylboronic acids. more...
- Published
- 2011
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23. Amphiphilic Block Copolymers Directed Interface Coassembly to Construct Multifunctional Microspheres with Magnetic Core and Monolayer Mesoporous Aluminosilicate Shell
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Xuanyu Yang, Yu Zhang, Xiu-Feng Hou, Xiaowei Cheng, Dongyuan Zhao, Yonghui Deng, Lei Yu, and Qin Yue
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Materials science ,Mechanical Engineering ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Tetraethyl orthosilicate ,chemistry.chemical_compound ,Adsorption ,chemistry ,Chemical engineering ,Mechanics of Materials ,Aluminosilicate ,Amphiphile ,Monolayer ,Copolymer ,General Materials Science ,0210 nano-technology ,Mesoporous material - Abstract
Core-shell magnetic porous microspheres have wide applications in drug delivery, catalysis and bioseparation, and so on. However, it is great challenge to controllably synthesize magnetic porous microspheres with uniform well-aligned accessible large mesopores (>10 nm) which are highly desired for applications involving immobilization or adsorption of large guest molecules or nanoobjects. In this study, a facile and general amphiphilic block copolymer directed interfacial coassembly strategy is developed to synthesize core-shell magnetic mesoporous microspheres with a monolayer of mesoporous shell of different composition (FDUcs-17D), such as core-shell magnetic mesoporous aluminosilicate (CS-MMAS), silica (CS-MMS), and zirconia-silica (CS-MMZS), open and large pores by employing polystyrene-block-poly (4-vinylpyridine) (PS-b-P4VP) as an interface structure directing agent and aluminum acetylacetonate (Al(acac)3 ), zirconium acetylacetonate, and tetraethyl orthosilicate as shell precursors. The obtained CS-MMAS microspheres possess magnetic core, perpendicular mesopores (20-32 nm) in the shell, high surface area (244.7 m2 g-1 ), and abundant acid sites (0.44 mmol g-1 ), and as a result, they exhibit superior performance in removal of organophosphorus pesticides (fenthion) with a fast adsorption dynamics and high adsorption capacity. CS-MMAS microspheres loaded with Au nanoparticles (≈3.5 nm) behavior as a highly active heterogeneous nanocatalyst for N-alkylation reaction for producing N-phenylbenzylamine with a selectivity and yields of over 90% and good magnetic recyclability. more...
- Published
- 2018
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24. Neutral Trinuclear Palladium(II) Metallocycles with Mixed Phosphane/Pyridine‐4‐thiolato Ligands and Their Catalytic Tests in Suzuki–Miyaura Coupling Reactions
- Author
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Hui Wang, Xu-Qing Guo, Xiao‐Yan Feng, Rui Zhong, and Xiu-Feng Hou
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Stereochemistry ,Ligand ,chemistry.chemical_element ,Crystal structure ,Nuclear magnetic resonance spectroscopy ,Medicinal chemistry ,Coupling reaction ,Catalysis ,Inorganic Chemistry ,Metal ,chemistry.chemical_compound ,chemistry ,visual_art ,Pyridine ,visual_art.visual_art_medium ,Palladium - Abstract
Three neutral trinuclear palladium(II) complexes [Ph 3 PPdCl(μ-4-PyS)] 3 (1), [Cy 3 PPdCl(μ-4-PyS)] 3 (2) and [(PhO) 3 PPdCl(μ-4-PyS)] 3 (3) (4-PyS = pyridine-4-thiolate) were self-assembled from corresponding metal fragments [R 3 PPdCl 2 ] 2 with lithium pyridine-4-thiolate (PySLi). The crystal structure reveals that complex 1 possesses a triangular macrocyclic structure in which the distances of Pd(1)··· Pd(2), Pd(2)···Pd(3) and Pd(3)···Pd(1) are 7.764, 7.684 and 7.944 A, respectively. An equilibrium between trinuclear complex 1 and mononuclear complex (Ph 3 P) 2 PdCl(4-PyS) (4) in solution through coordination and de-coordination of the PPh 3 ligand is confirmed by 31 P NMR spectroscopy. A comparative study on the Suzuki-Miyaura coupling reaction showed that complexes 1 and 2 are more active precatalysts than [R 3 PPdCl 2 ] 2 complexes without a PyS group. more...
- Published
- 2009
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25. Synthesis and Structure of Half-Sandwich Pyridine-2-thiolato Cobalt(III) and Rhodium(III) Complexes and Their Reactivity toward Monodentate or Bidentate 1,2-Dicarba-closo-dodecaborane Thiolate Ligands
- Author
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Peng-Cheng Zhang, Shu Liu, Hui Wang, Xiu-Feng Hou, and Linhong Weng
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Denticity ,Organic Chemistry ,Inorganic chemistry ,chemistry.chemical_element ,Medicinal chemistry ,Rhodium ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Pyridine ,Lithium ,Reactivity (chemistry) ,Transition metal thiolate complex ,Physical and Theoretical Chemistry ,Cobalt ,Methyl group - Abstract
The half-sandwich cobalt(III) and rhodium(III) complexes with pyridine-2-thiolato ligands Cp*Co(PyS)I (3) and Cp*Rh(PyS)Cl (4) [Cp* = pentamethylcyclopentadienyl, PyS = pyridine-2-thiolate] were obtained by reactions of lithium pyridine-2-thiolate (PySLi) with Cp*Co(CO)I2 (1) and [Cp*RhCl2]2 (2), respectively, in high yield. Complexes 3 and 4 reacted with monodentate LiSC2(H)B10H10 to give Cp*Co(PyS)[SC2(H)B10H10] (5) and Cp*Rh(PyS)[SC2(H)B10H10] (6), respectively. Reactions of 3 and 4 with Li2S2C2B10H10 resulted in C−H activation of a methyl group of the Cp* of the cobalt complex to give [(C5Me4CH2SC5H4N)Co(S2C2B10H10)] (7). No such activation of a methyl group of the Cp* of the rhodium complex occurred, and Cp*Rh[Py(H)S](S2C2B10H10) (8) was the product. more...
- Published
- 2008
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26. Synthesis and molecular structure of hexanuclear organotitanium ion complex
- Author
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Peng-Cheng Zhang, Guo-Xin Jin, Xiu-Feng Hou, and Shu Liu
- Subjects
Chemistry ,Organic Chemistry ,Inorganic chemistry ,chemistry.chemical_element ,Biochemistry ,Inorganic Chemistry ,Metal ,Dilithium ,Crystallography ,chemistry.chemical_compound ,Octahedron ,Cyclopentadienyl complex ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Cluster (physics) ,Carborane ,Molecule ,Physical and Theoretical Chemistry ,Titanium - Abstract
The reaction of bis[(2-methoxyethyl)cyclopentadienyl] titanium dichloride with dilithium dithiolato carborane in THF give a novel hexanuclear organotitanium ion complex [ Cp 6 ′ Ti 6 ( μ 3 -O ) 8 ] [ C 2 B 10 H 10 ( μ - S 2 ) 2 C 2 B 9 H 10 ] 2 (Cp′ = C5H4CH2CH2OCH3) ([1][2]2) as yellow crystal blocks. The cation [1]2+ has an octahedral metallic skeleton of six titanium atoms with the tricoordinated oxygen (μ3-O) and the anion [2]− consists of two S2 bridged 7,8-dicarbaundecaborate cluster and 1,2-dicarba-closo-dodecaborate cluster. more...
- Published
- 2007
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27. Half-sandwich cyclopentadienyl rhodium complexes bearing pendant sulfur or oxygen ligands and their catalytic behaviors in ethylene polymerization
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Yin-Qiang Cheng, Xiu-Feng Hou, Xin Wang, and Guo-Xin Jin
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Ethylene ,Ligand ,Organic Chemistry ,chemistry.chemical_element ,Polyethylene ,Photochemistry ,Biochemistry ,Rhodium ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Cyclopentadienyl complex ,Polymerization ,Polymer chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,Norbornene - Abstract
Two half-sandwich rhodium complexes with sulfur or oxygen functionalized cyclopentadienyl ligands [η5-C5H4(CH2)2SCH2CH3]RhI2 3, {[η5-C5H4(CH2)2OCH3]RhI2}2 4 have been synthesized and characterized by IR, 1H-NMR spectra and Elemental analyses. The molecular structures of complexes 3 and 4 have been determined by X-ray crystallographic analysis. Complexes 3, 4 with a pendent arm on cyclopentadienyl ligand have been tested as catalysts for ethylene and norbornene polymerization in the presence of MAO. Complexes 3 and 4 kept high activities of ca. 106 g PE mol−1 Rh h−1 with morderate molecular weight (Mw ≈ 105 g mol−1) of polyethylene in the ethylene polymerization. Catalytic activities, molecular weights of polyethylene have been investigated under the various reaction conditions. more...
- Published
- 2005
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28. Binuclear complexes of rhodium (I) bridged by 1,2-dicarba-closo-dodecaborane-1,2-dichalcogenolato ligands: molecular structures of the complexes [Rh2(COD)2(μ2-E2C2(B10H10))] [E=S, Se] and [Rh2(CO)4(μ2-S2C2(B10H10))]
- Author
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Linhong Weng, Guo-Xin Jin, Xiu-Feng Hou, and Shuyi Cai
- Subjects
Inorganic Chemistry ,Dilithium ,Crystallography ,chemistry.chemical_compound ,chemistry ,Organic Chemistry ,Materials Chemistry ,chemistry.chemical_element ,Infrared spectroscopy ,Carborane ,Physical and Theoretical Chemistry ,Biochemistry ,Rhodium - Abstract
Four new dichalcogenolate carborane bridged binuclear rhodium(I) complexes [Rh2(COD)2(μ2-E2C2(B10H10))] [COD = cycloocta-1,5-diene (C8H12), E = S (2a), Se (2b)] and [Rh2(CO)2(μ2-E2C2(B10H10))] [E = S (3a), Se (3b)] have been prepared by the reactions of the dilithium dichalcogenolate carboranes Li2E2C2B10H10 (E = S, Se) with [Rh(COD)Cl]2 or [Rh(CO)2Cl]2, respectively. The complexes have been fully characterized by 1H, 13C, 11B NMR and IR spectroscopy as well as by element analyses. The molecular structures of 2a, 2b and 3a have been determined by single-crystal X-ray diffraction analyses, which show the strong metal–metal interaction between two rhodium atoms. more...
- Published
- 2005
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29. Synthesis and Structure of Heterometallic Clusters (IrCo2, IrFe) Containing Bridging 1,2-Dicarba-closo-dodecaborane-1,2-dichalocogenolato Ligands
- Author
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Guo-Xin Jin, Xiu-Feng Hou, Jianqiang Wang, and Linhong Weng
- Subjects
Inorganic Chemistry ,chemistry.chemical_compound ,Crystallography ,chemistry ,Organic Chemistry ,chemistry.chemical_element ,Iridium ,Physical and Theoretical Chemistry ,Toluene - Abstract
The 16-electron half-sandwich iridium complexes [Cp*Ir{E 2 C 2 (B 1 0 H 1 0 )}] [E = S (la), Se (1b)] (Cp* = η 5 -C 5 Me 5 ) [Cp*Ir[E 2 C 2 (B 1 0 H 1 0 )] = η 5 -pentamethylcyclopentadienyl-[1,2-dicarba-closo-dodecaborane(12)-dichalcogenolato]iridium] reacted with Co 2 (CO) 8 in toluene solution to afford the trinuclear clusters [Cp*Ir{E 2 C 2 (B 1 0 H 1 0 )}]{Co 2 (CO) 5 } [E = S (2a), Se (2b)] and mononuclear complexes [Cp*Ir(CO){E 2 C 2 (B 1 0 H 1 0 )}] [E = S (3a), Se (3b)] as byproducts. Compounds 2a and 2b contain closed IrCo 2 triangle geometry with one Co-Co and two Ir-Co bonds. The dinuclear IrFe complexes [Cp*Ir{E 2 C 2 (B 1 0 H 1 0 )}]{Fe(CO) 3 } [E = S (4a), Se (4b)] were obtained from the reactions of la and 1b with Fe(CO) 5 in the presence of Me 3 -NO. The molecular structures of 2a, 2b, and 4b have been determined by X-ray crystallography. more...
- Published
- 2005
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30. Sulfur and oxygen functionalized cyclopentadienyl half-sandwich cobalt complexes with 1,2-dicarba-closo-dodecaborane-1,2-dichalcogenolato ligands
- Author
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Xiao-Chuan Wang, Jianqiang Wang, Guo-Xin Jin, and Xiu-Feng Hou
- Subjects
Stereochemistry ,Organic Chemistry ,chemistry.chemical_element ,Biochemistry ,Medicinal chemistry ,Sulfur ,Oxygen ,Inorganic Chemistry ,Dilithium ,chemistry.chemical_compound ,chemistry ,Cyclopentadienyl complex ,Intramolecular force ,Materials Chemistry ,Carborane ,Physical and Theoretical Chemistry ,Cobalt - Abstract
Sulfur and oxygen functionalized cyclopentandienyl half-sandwich cobalt dicarbonyl complexes [η5-C5H4(CH2)2SCH2CH3]Co(CO)2 (3) and [η5-C5H4(CH2)2OCH3]Co(CO)2 (7) were prepared. Oxidation of 3 or 7 with I2 led to formation of 18-electron complexes [η5-C5H4(CH2)2SCH2CH3]CoI2 (4) and [η5-C5H4(CH2)2OCH3]Co(CO)I2 (8). The reactions of diiodide complex (4) with dilithium 1,2-dicarba-closo-dodecaborane(12)-1,2-dichalcogenolates [(THF)3LiE2C2B10H10Li(THF)]2 [E=S (1a), Se (1b)] afforded 18-electron mononuclear complexes [η5-C5H4(CH2)2SCH2CH3]Co(E2C2B10H10) [E=S (5a), Se (5b)] in which sulfur atoms of side-chain were attached via an intramolecular coordination. Complex 7 reacted with 1a and 1b to give the binuclear complexes {[η5-C5H4(CH2)2OCH3]Co(E2C2B10H10)}2 [E=S (10a), Se (10b)]. The molecular structures of 5a and 10b were determined by X-ray crystallographic analysis. According to the X-ray structure analyses, 10b contains two o-carborane diselenolate bridges, and each Cp′Co fragment is attached to one terminal and two bridging selenolato ligands. The central Co2Se2 four-membered ring is planar, and the direct metal–metal interaction is absent. more...
- Published
- 2004
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31. Di-μ-cyanato-bis[(cyanato-κN)(tetramethylethylenediamine-κ2N,N′)copper(II)] andcatena-poly[[μ3-cyanato-κ3O:N:N-bis[(cyanato-κN)(1,3-diaminopropane-κ2N,N′)copper(II)]]-μ3-cyanato-κ3N:N:O]
- Author
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Xi Geng Zhou, Jun Luo, Lin Hong Weng, and Xiu Feng Hou
- Subjects
Chemistry ,Hydrogen bond ,Stereochemistry ,Dimer ,1,3-Diaminopropane ,General Medicine ,Crystal structure ,Tetramethylethylenediamine ,Cyanate ,General Biochemistry, Genetics and Molecular Biology ,chemistry.chemical_compound ,Crystallography ,Diamine ,Molecule - Abstract
The two title CuII complexes, [Cu2(NCO)4(tmeda)2] (tmeda is tetramethylethylenediamine, C6H16N2), (I), and [Cu(NCO)2(pn)]n (pn is 1,3-diaminopropane, C3H10N2), (II), have been synthesized and their crystal structures determined. In (I), which lies about an inversion centre, each Cu centre possesses a distorted tetragonal–pyramidal geometry with four basal N atoms from two cyanate anions [Cu—N = 1.945 (2) and 1.948 (3) A] and one tmeda molecule [Cu—N = 2.053 (2) and 2.071 (2) A], and one axial O atom [Cu—O = 2.737 (3) A] from another cyanate anion. The two neighbouring Cu atoms in (I) are joined by a pair of cyanates in an end-to-end fashion, forming a dimer. In (II), each Cu centre adopts a distorted square-bipyramidal geometry, with four equatorial N atoms from two cyanates [Cu—N = 1.988 (2) and 2.007 (3) A] and a pn ligand [Cu—N = 1.996 (3) and 2.011 (3) A], and one apical N atom [Cu—N = 2.437 (3) A] and an apical O atom [Cu—O = 2.900 (3) A] from two cyanates. In contrast with (I), the two neighbouring Cu atoms in (II) are bridged by two cyanates in an end-on fashion, to form a centrosymmetric dimeric unit. These units are further crosslinked, forming a two-dimensional network structure, via weak interactions between the bridging cyanate O atom and a neighbouring Cu atom, plus interactions of the amine H atoms with the cyanate O atoms and the terminal cyanate N atom. more...
- Published
- 2003
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32. Synthesis and reactivity impact from electron-withdrawing substituent on the cyclopentadienyl ligand of cobalt(I)–(III) complexes
- Author
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You-Feng Xu, Chong-Zhi Tang, Zhen Pang, and Xiu-Feng Hou
- Subjects
Ligand ,Stereochemistry ,Organic Chemistry ,Substituent ,chemistry.chemical_element ,Biochemistry ,Sodium amalgam ,Medicinal chemistry ,Inorganic Chemistry ,chemistry.chemical_compound ,Cyclopentadienyl complex ,chemistry ,Cobaltocene ,Materials Chemistry ,Polar effect ,Reactivity (chemistry) ,Physical and Theoretical Chemistry ,Cobalt - Abstract
Cobaltocene [η 5 -C 5 H 4 COOC(CH 3 )CH 2 ] 2 Co ( 1 ) was synthesized from CoCl 2 ·6H 2 O at −30 °C. 1 showed two reversible redox potentials at −0.335 and −1.418 V, respectively. It was found that the electron-withdrawing substituent on the cyclopentadienyl ligand facilitated the formation of cobaltocene quantitatively. (η 5 -C 5 H 4 COOCH 3 )Co(C 8 H 12 ) ( 2 ) was synthesized from 1 at −50 °C under sodium amalgam and the structure of 2 was determined by single-crystal X-ray diffraction. The change of the electron-withdrawing group from the carboisopropenyloxy to the carbomethoxy group on the cyclopentadienyl ligand is also discussed. more...
- Published
- 2003
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33. Bis(dicyanamido)(diethylenetriamine-κ3N)copper(II) and (dicyanamido)(triethylenetetramine-κ4N)copper(II) dicyanamide
- Author
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Jun Luo, Xiu-Feng Hou, Linhong Weng, and Xigeng Zhou
- Subjects
Denticity ,biology ,Chemistry ,Hydrogen bond ,General Medicine ,Crystal structure ,General Biochemistry, Genetics and Molecular Biology ,chemistry.chemical_compound ,Crystallography ,Triethylenetetramine ,Diethylenetriamine ,biology.protein ,Molecule ,Dicyanamide ,Organic anion - Abstract
Two new complexes, [Cu(C(2)N(3))(2)(dien)] (dien is diethylenetriamine, C(4)H(13)N(3)), (I), and [Cu(C(2)N(3))(trien)](C(2)N(3)) (trien is triethylenetetramine, C(6)H(18)N(4)), (II), have been characterized by single-crystal X-ray diffraction. Both complexes display a distorted tetragonal-pyramidal geometry. In (I), the Cu atom is coordinated in the basal plane by three diethylenetriamine N atoms [Cu-N = 2.000 (2), 2.004 (2) and 2.025 (2) A] and one terminal N atom [Cu-N = 1.974 (2) A] from one monodentate dicyanamide group, and in the apical position by one terminal N atom [Cu-N = 2.280 (2) A] from the other monodentate dicyanamide group. In (II), the Cu atom is surrounded by four triethylenetetramine N atoms [Cu-N = 2.012 (2), 2.014 (2), 2.019 (2) and 2.031 (2) A in the basal plane] and a terminal N atom [Cu-N = 2.130 (2) A in the apical site] from one monodentate dicyanamide group. The other dicyanamide anion is not directly coordinated to the metal atom. In both (I) and (II), hydrogen-bond interactions between the uncoordinated terminal N atoms of two dicyanamide ions and the amine H atoms lead to the formation of three-dimensional networks. more...
- Published
- 2003
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34. Synthesis, Characterization and Electrochemical Properties of Substituted Half-Sandwich Cobalt(I) Complexes
- Author
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Zu-En Huang, Zhen Pang, Ruifang Cai, Ruyi Ruan, and Xiu-Feng Hou
- Subjects
Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Stereochemistry ,chemistry.chemical_element ,Reaction intermediate ,Physical and Theoretical Chemistry ,Electrochemistry ,Cobalt ,Medicinal chemistry ,Phosphine - Abstract
Organocobalt compounds C5H4RCoLL' (2a),(2b), (2b') and (2c) (L = CO, L' = PR3; a, R = -COOC(CH3)[dbnd]CH2; b, R = -COOCH2C6H5; c, R = -COOCH2CH[dbnd]CH2.) were prepared and characterized. The electronic spectra and the electrochemical properties of compounds (2a), (2b), (2b'), (2c) and their analogues (la), (lb), (lc), (ld) (L = L'[dbnd]CO; d, R = -CH2COOCH2CH[dbnd]CH2) and (3) (L = L' = PR3, R = -COOCH2C6H5) were also studied. It was found that (2a), (2b), (2b'), (2c) exhibited two reversible peaks during electrochemical oxidation which were attributed to the formation of two reaction intermediates. Their dicarbonyl or bis(phosphine) analogues did not show such reversible peaks during electrochemical oxidation. The compounds (2a), (2b), (2b') and (2c) exhibited the best ability of anti-oxidation among the three types of the organocobalt compounds. more...
- Published
- 2000
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35. A novel bonding mode of tetrazolate ligand to a metal: synthesis and structural characterization of 5-phenyltetrazolate organolanthanide complexes: [{(C5H4Me)(C5H5)LnTz}2][{(C5H4Me)2LnTz}2] (Ln=Dy, Gd) and [(C5H4Me)2LnTz)]2 (Ln=Yb, Er)
- Author
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Xiao-Jiang Feng, Lixin Zhang, Xiao-Ying Huang, Xigeng Zhou, Zu-En Huang, Ruifang Cai, and Xiu-Feng Hou
- Subjects
Ytterbium ,Stereochemistry ,Ligand ,Gadolinium ,Dimer ,Organic Chemistry ,chemistry.chemical_element ,Biochemistry ,Inorganic Chemistry ,Crystallography ,chemistry.chemical_compound ,chemistry ,Atom ,Materials Chemistry ,Dysprosium ,Molecule ,Chelation ,Physical and Theoretical Chemistry - Abstract
Reaction of (C 5 H 4 Me) 3 Ln and TzH (5-phenyl-1H-tetrazole) in THF affords complexes [(C 5 H 4 Me) 2 LnTz] 2 [Ln=Yb ( 1 ), Er ( 2 )]. 1 crystallized in the space group C 2/ c , with unit cell dimensions a =25.596(2), b =8.342(1), c =21.573(2) A, β =129.322(9)°. V =3563.5(8) A 3 and Z =8 for D c =1.776 g cm −3 . Least-squares refinement of the model based on 2700 reflections converged to a final R =0.031. The molecule is centrosymmetric dimer in which each ytterbium atom is coordinated by two methylcyclopentadienyl groups and three nitrogen atoms of the bridging Tz ligands to form a distorted trigonal-bipyramidal geometry. When there is a small amount of (C 5 H 4 Me) 2 Ln(C 5 H 5 ) in (C 5 H 4 Me) 3 Ln, the 1:1 complexes [{(C 5 H 4 Me)(C 5 H 5 )LnTz} 2 ][{(C 5 H 4 Me) 2 LnTz} 2 ] (Ln=Dy ( 3 ), Gd ( 4 )) were obtained in crystalline form. 3 and 4 crystallize as isomorphous crystals of space group P 1 with the following unit cell parameters ( 3 / 4 ): a =9.374(2)/9.420(4), b =13.048(2)/13.215(4), c =16.542(4)/16.677(5) A, a =86.95(2)/87.24(2), β =74.61(1)/74.50(3), γ =77.31(1)/77.08(3)°, Y =1903(1)/1950(1) A 3 , Z =2, D c =1.602/1.545 g cm −3 , R =0.046/0.051. Crystallographic data for 3 and 4 show that there are two disconnected structural units [(C 5 H 4 Me)(C 5 H 5 )Ln( μ - η 1 : η 2 -Tz)] 2 and [(C 5 H 4 Me) 2 Ln( μ - η 1 : η 2 -Tz)] 2 , crystallizing in one asymmetrical unit, each of which is tetrazolate-bridged dimer and has an inversion center. The bridging unit Ln 2 N 6 is planar. All three structures reveal an unusual bonding mode of the tetrazolate ligand, in which the tetrazolate group acts as both a bridging and chelating ligand, with the nitrogen atoms at 1, 2 and 3-position taking part in bonding. more...
- Published
- 1998
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36. Olefin polymerization behavior of the cyclopentadienyl cobalt complexes bearing pendant sulfur or oxygen ligands
- Author
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Guo-Xin Jin, Peng-Cheng Zhang, Xiu-Feng Hou, and Yin-Qiang Cheng
- Subjects
chemistry.chemical_element ,Polyethylene ,Sulfur ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Polymerization ,Cyclopentadienyl complex ,Polymer chemistry ,Materials Chemistry ,Molecule ,Coordination polymerization ,Organic chemistry ,Physical and Theoretical Chemistry ,Cobalt - Abstract
Four half-sandwich cobalt complexes bearing pendant sulfur or oxygen ligands have been reported and tested as catalysts for olefin polymerization in the presence of MAO. The molecular structure of complexes 1 has been determined by X-ray crystallographic analysis. Complexes 1 and 2 exhibited high activities of up to 106 g PE mol−1Co h−1 with moderate molecular weight (Mw ≈ 104 g mol−1) of polyethylene in the ethylene polymerization. more...
- Published
- 2006
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37. ChemInform Abstract: An Efficient and Recyclable Catalyst for N-Alkylation of Amines and β-Alkylation of Secondary Alcohols with Primary Alcohols: SBA-15 Supported N-Heterocyclic Carbene Iridium Complex
- Author
-
Li-Hua Cai, Zi-Wei Gao, Xiu-Feng Hou, Dong Wang, Ya-Nong Wang, Chen-Xi Wang, Rui Zhong, Xiao-Han Zhu, and Xu-Qing Guo
- Subjects
Primary (chemistry) ,chemistry.chemical_element ,General Medicine ,Alkylation ,Recyclable catalyst ,law.invention ,Catalysis ,chemistry.chemical_compound ,chemistry ,law ,Organic chemistry ,Iridium ,Carbene ,Filtration - Abstract
The catalyst can be recovered by simple filtration and reused eight or twelve times (β-alkylation resp.
- Published
- 2013
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38. Generation of 6H-benzo[f]cyclopenta[d][1,2]thiazepine 5,5-dioxides via a palladium-catalyzed reaction of 2-(2-alkynyl)benzenesulfonamide
- Author
-
Xiu-Feng Hou, Huanhuan Wang, Yong Luo, and Jie Wu
- Subjects
Sulfonamides ,Stereochemistry ,Thiazepines ,Molecular Conformation ,chemistry.chemical_element ,Crystallography, X-Ray ,Medicinal chemistry ,Catalysis ,D-1 ,Inorganic Chemistry ,chemistry.chemical_compound ,Cascade reaction ,chemistry ,Bromide ,Alkynes ,Thiazepine ,Palladium - Abstract
An efficient approach for the assembly of 6H-benzo[f]cyclopenta[d][1,2]thiazepine 5,5-dioxides via a palladium-catalyzed tandem reaction of 2-(2-alkynyl)benzenesulfonamide with 2-alkynylvinyl bromide is reported. This transformation proceeds smoothly through a double carbopalladation with high efficiency. more...
- Published
- 2012
39. Palladium, iridium and ruthenium complexes with acyclic imino-N-heterocyclic carbenes and their application in aqua-phase Suzuki-Miyaura cross-coupling reaction and transfer hydrogenation
- Author
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Zhenxia Chen, Ya-Nong Wang, Xu-Qing Guo, Li-Hua Cai, Dong Wang, and Xiu-Feng Hou
- Subjects
Inorganic chemistry ,chemistry.chemical_element ,Transfer hydrogenation ,Medicinal chemistry ,Coupling reaction ,Catalysis ,Ruthenium ,Inorganic Chemistry ,chemistry.chemical_compound ,Transmetalation ,chemistry ,Iridium ,Carbene ,Palladium - Abstract
Palladium (4a–4c), iridium (5a–5c) and ruthenium (6a–6c) complexes have been prepared by in situ transmetalation from the corresponding silver complexes of acyclic imino-functionalized imidazolium chlorides [1-(Me)-imidazolium-3-{C(p-CH(3)-Ph)=N(Ar)}]Cl (3) (Ar = 2,4,6-trimethylphenyl (3a), 2,6-diisopropylphenyl (3b) and phenyl (3c)) with [Pd(COD)Cl(2)], [Cp*IrCl(2)](2) or [Ru(p-cymene)Cl(2)](2), respectively. Iridium and ruthenium complexes, 5a[PF(6)]–5c[PF(6)], 6a[PF(6)]–6c[PF(6)], 6c[BF(4)], 6c[BPh(4)] and 6c[NTf(2)], were obtained directly from 5a–5c and 6a–6c through an anion-exchange process with KPF(6), NaBF(4), NaBPh(4) and LiNTf(2) (bis(trifluoromethylsulfonyl)imide lithium), respectively. All complexes were characterized by FT-IR, (1)H and (13)C NMR spectroscopy and elemental analysis. Crystal structures of 4a, 5a and 6c[NTf(2)], and show that five-membered chelate ring is formed in these complexes by the coordination of the carbene carbon and the imino nitrogen atom, and the latter two are cationic compounds with Cl(-) and NTf(2)(-) as counteranion respectively. The catalytic performance of Pd complexes for Suzuki-Miyaura cross-coupling reactions in pure water and Ir and Ru complexes for transfer hydrogenation of ketones and imines was tested in a wide scope of substrates. Pd complex 4b with the largest steric hinder exhibited the best performance to gain moderate to excellent yields on catalyzing Suzuki-Miyaura cross-coupling of aryl chlorides and arylboronic acids in water. While in transfer hydrogenation of various ketones, all the Ir and Ru complexes were effective with good to excellent yields. Among all these complexes, 6c[PF(6)] was found most effective, and moderate yields could be obtained even in the transfer hydrogenation of imines. Moreover, different counteranions of Ru complexes are influential on catalyzing the transfer hydrogenation, with the sequence of PF(6)(-) ≈ BF(4)(-)BPh(4)(-)Cl(-)NTf(2)(-). more...
- Published
- 2012
40. ChemInform Abstract: Effect of Counterions and Central Cores of Tripodal Imidazolium Salts on Palladium-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions
- Author
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Xu-Qing Guo, Xiu-Feng Hou, Rui Zhong, and Ya-Nong Wang
- Subjects
chemistry.chemical_classification ,Ligand ,Aryl ,chemistry.chemical_element ,Salt (chemistry) ,General Medicine ,Coupling reaction ,Catalysis ,chemistry.chemical_compound ,chemistry ,Hexafluorophosphate ,Polymer chemistry ,Organic chemistry ,Counterion ,Palladium - Abstract
Among a variety of benzene-, nitrogen-, or carbon-centered tripodal imidazolium salts bearing different counterions, the benzene-centered hexafluorophosphate salt (TIMB) shows the best activity as ligand in the Suzuki—Miyaura cross coupling of aryl iodides or bromides (I) with arylboronic acids (II). more...
- Published
- 2011
- Full Text
- View/download PDF
41. Binuclear half-sandwich cobalt(III) and rhodium(III) ortho-carboranedichalocogenolato complexes with ether chain-bridged bis(cyclopentadienyl) ligand
- Author
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Shu Liu, Hui Wang, Yin-Qiang Chen, Xiu-Feng Hou, and Guo-Xin Jin
- Subjects
Denticity ,Stereochemistry ,chemistry.chemical_element ,Ether ,Medicinal chemistry ,Rhodium ,Inorganic Chemistry ,Dilithium ,NMR spectra database ,Sodium cyclopentadienide ,chemistry.chemical_compound ,chemistry ,Cyclopentadienyl complex ,Cobalt - Abstract
1, 1'-(3-Oxapentamethylene)dicyclopentadiene [O(CH(2)CH(2)C(5)H(5))(2)], containing a flexible chain-bridged group, was synthesized by the reaction of sodium cyclopentadienide with bis(2-chloroethyl) ether through a slightly modified literature procedure. Furthermore, the binuclear cobalt(III) complex O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(CO)I(2)](2) and insoluble polynuclear rhodium(III) complex {O[CH(2)CH(2)(eta(5)-C(5)H(4))RhI(2)](2)}(n) were obtained from reactions of with the corresponding metal fragments and they react easily with PPh(3) to give binuclear metal complexes, O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(PPh(3))I(2)](2) and O[CH(2)CH(2)(eta(5)-C(5)H(4))Rh(PPh(3))I(2)](2), respectively. Complexes react with bidentate dilithium dichalcogenolato ortho-carborane to give eight binuclear half-sandwich ortho-carboranedichalcogenolato cobalt(III) and rhodium(III) complexes O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(PPh(3))(E(2)C(2)B(10)H(10))](2) (E = S and Se), O[CH(2)CH(2)(eta(5)-C(5)H(4))](2)Co(2)(E(2)C(2)B(10)H(10)) (E = S and Se), O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(E(2)C(2)B(10)H(10))](2) (E = S and Se and O[CH(2)CH(2)(eta(5)-C(5)H(4))Rh(PPh(3))(E(2)C(2)B(10)H(10))](2) (E = S and Se). All complexes have been characterized by elemental analyses, NMR spectra ((1)H, (13)C, (31)P and (11)B NMR) and IR spectroscopy. The molecular structures were determined by X-ray diffractometry. more...
- Published
- 2006
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