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1.
Jan Svoboda Jan Sedláček Jiří Zedník Gita Dvořáková Olga Trhlíková Dana Rédrová Hynek Balcar Jiří Vohlídal 《Journal of polymer science. Part A, Polymer chemistry》2008,46(8):2776-2787
3‐Ethynylthiophene (3ETh) was polymerized with Rh(I) complexes: [Rh(cod)acac], [Rh(nbd)acac], [Rh(cod)Cl]2, and [Rh(nbd)Cl]2 (cod is η2:η2‐cycloocta‐1,5‐diene and nbd η2:η2‐norborna‐2,5‐diene), used as homogeneous catalysts and with the last two complexes anchored on mesoporous polybenzimidazole (PBI) beads: [Rh(cod)Cl]2/PBI and [Rh(nbd)Cl]2/PBI used as heterogeneous catalysts. All tested catalyst systems give high‐cis poly(3ETh). In situ NMR study of homogeneous polymerizations induced with [Rh(cod)acac] and [Rh(nbd)acac] complexes has revealed: (i) a transformation of acac ligands into free acetylacetone (Hacac) occurring since the early stage of polymerization, which suggests that this reaction is part of the initiation, (ii) that the initiation is rather slow in both of these polymerization systems, and (iii) a release of cod ligand from [Rh(cod)acac] complex but no release of nbd ligand from [Rh(nbd)acac] complex during the polymerization. The stability of diene ligand binding to Rh‐atom in [Rh(diene)acac] catalysts remarkably affects only the molecular weight but not the yield of poly(3ETh). The heterogeneous catalyst systems also provide high‐cis poly(3ETh), which is of very low contamination with catalyst residues since a leaching of anchored Rh complexes is negligible. The course of heterogeneous polymerizations is somewhat affected by limitations arising from the diffusion of monomer inside catalyst beads. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2776–2787, 2008 相似文献
2.
Peng Zhou Ning Li Yuguang Chao Weiyu Zhang Fan Lv Kai Wang Wenxiu Yang Peng Gao Shaojun Guo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14322-14326
Noble metal single atoms coordinated with highly electronegative atoms, especially N and O, often suffer from an electron‐deficient state or poor stability, greatly limiting their wide application in the field of catalysis. Herein we demonstrate a new PH3‐promoted strategy for the effective transformation of noble metal nanoparticles (MNPs, M=Ru, Rh, Pd) at a low temperature (400 °C) into a class of thermally stabilized phosphorus‐coordinated metal single atoms (MPSAs) on g‐C3N4 nanosheets via the strong Lewis acid–base interaction between PH3 and the noble metal. Experimental work along with theoretical simulations confirm that the obtained Pd single atoms supported on g‐C3N4 nanosheets exist in the form of PdP2 with a novel electron‐rich feature, conceptionally different from the well‐known single atoms with an electron‐deficient state. As a result of this new electronic property, PdP2‐loaded g‐C3N4 nanosheets exhibit 4 times higher photocatalytic H2 production activity than the state‐of‐art N‐coordinated PdSAs supported on g‐C3N4 nanosheets. This enhanced photocatalytic activity of phosphorus‐coordinated metal single atoms with an electron‐rich state was quite general, and also observed for other active noble metal single atom catalysts, such as Ru and Rh. 相似文献
3.
Sujittra Youngme Jaturong Phatchimkun Samran Prabpai Chaveng Pakawatchai Palangpon Kongsaeree 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(2):m45-m47
The two new title complexes, [Cu(N3)(dpyam)2]PF6 (dpyam is di‐2‐pyridylamine, C10H11N3), (I), and [Cu(N3)(dpyam)2]Cl·4H2O, (II), respectively, have been characterized by single‐crystal X‐ray diffraction. Both complexes display a distorted square‐pyramidal geometry. Each Cu atom is coordinated in the basal plane by three dpyam N atoms and one azide N atom in equatorial positions, and by another N atom from the dpyam group in the apical position. In complex (I), the one‐dimensional supramolecular architecture is assembled via hydrogen‐bonding interactions between the amine N atom and terminal azide N atoms and the F atoms of the PF6− anion. For complex (II), hydrogen‐bonding interactions between the amine N atom, the Cl− anion and water O atoms result in a two‐dimensional lattice. 相似文献
4.
Mamiko Odoko Kyouta Yamamoto Nobuo Okabe 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):m506-m508
In the title complex, {[Cu(C6H5O3)Cl(H2O)]·H2O}n, the CuII atom has a deformed square‐pyramidal coordination geometry formed by two O atoms of the maltolate ligand, two bridging Cl atoms and the coordinated water O atom. The Cu atoms are bridged by Cl atoms to form a polymeric chain. The deprotonated hydroxyl and ketone O atoms of the maltolate ligand form a five‐membered chelate ring with the Cu atom. Stacking interactions and hydrogen bonds exist in the crystal. 相似文献
5.
Bidyut B. Sarma Jonglack Kim Jonas Amsler Giovanni Agostini Claudia Weidenthaler Norbert Pfnder Raul Arenal Patricia Concepcin Philipp Plessow Felix Studt Gonzalo Prieto 《Angewandte Chemie (International ed. in English)》2020,59(14):5806-5815
Realizing the full potential of oxide‐supported single‐atom metal catalysts (SACs) is key to successfully bridge the gap between the fields of homogeneous and heterogeneous catalysis. Here we show that the one‐pot combination of Ru1/CeO2 and Rh1/CeO2 SACs enables a highly selective olefin isomerization‐hydrosilylation tandem process, hitherto restricted to molecular catalysts in solution. Individually, monoatomic Ru and Rh sites show a remarkable reaction specificity for olefin double‐bond migration and anti‐Markovnikov α‐olefin hydrosilylation, respectively. First‐principles DFT calculations ascribe such selectivity to differences in the binding strength of the olefin substrate to the monoatomic metal centers. The single‐pot cooperation of the two SACs allows the production of terminal organosilane compounds with high regio‐selectivity (>95 %) even from industrially‐relevant complex mixtures of terminal and internal olefins, alongside a straightforward catalyst recycling and reuse. These results demonstrate the significance of oxide‐supported single‐atom metal catalysts in tandem catalytic reactions, which are central for the intensification of chemical processes. 相似文献
6.
Maurice Abou Rida Joseph Saikaili Anthony K. Smith Alain Thozet 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):352-353
The title compound, dicarbonyl‐1κ2C‐di‐μ‐chloro‐1:2κ4Cl‐[cis,cis‐2(η4)‐1,5‐cyclooctadiene]dirhodium(I), [Rh2Cl2(C8H12)(CO)2], consists of a dichloro‐bridged dimer of rhodium, with a non‐bonded Rh?Rh distance of 3.284 (2) Å. One Rh atom is coordinated to two carbonyl ligands, while the other Rh atom is coordinated to the cyclooctadiene moiety. 相似文献
7.
Colourless crystals of the title compound, [Cd2(C7H4IO2)4(C12H10N2)(H2O)2]n, were obtained by the self‐assembly of Cd(NO3)2·4H2O, 1,2‐bis(pyridin‐4‐yl)ethene (bpe) and 4‐iodobenzoic acid (4‐IBA). Each CdII atom is seven‐coordinated in a pentagonal–bipyramidal coordination environment by four carboxylate O atoms from two different 4‐IBA ligands, two O atoms from two water molecules and one N atom from a bpe ligand. The CdII centres are bridged by the aqua molecules and bpe ligands, which lie across centres of inversion, to give a two‐dimensional net. Topologically, taking the CdII atoms as nodes and the μ‐aqua and μ‐bpe ligands as linkers, the two‐dimensional structure can be simplified as a (6,3) network. 相似文献
8.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(6):470-475
The 2‐methylbiphenyl‐4,4′‐dicarboxylate (mbpdc2−) ligand has versatile coordination modes and can be used to construct multinuclear structures. Despite this, reports of the synthesis of coordination complexes involving this ligand are scarce. The title compound, poly[[triaquadi‐μ3‐hydroxido‐hexakis(μ4‐2‐methylbiphenyl‐4,4′‐dicarboxylato)calcium(II)hexazinc(II)] monohydrate], {[CaZn6(C15H10O4)6(OH)2(H2O)3]·H2O}n , has been prepared by the hydrothermal assembly of Zn(NO3)2·6H2O, CaCl2 and 2‐methylbiphenyl‐4,4′‐dicarboxylic acid. Two ZnII atoms adopt a four‐coordinated distorted tetrahedral geometry by bonding to three O atoms from three different 2‐methylbiphenyl‐4,4′‐dicarboxylate (mbpdc2−) dianionic ligands and one bridging hydroxide O atom. For the remaining ZnII atom, a five‐coordinate environment is completed half the time by one carboxylate O atom, and then the same carboxylate O atom and an aqua O atom are present the other half of the time, giving a six‐coordinate environment. The CaII atom is coordinated by six O atoms to give an octahedral coordination geometry. The supramolecular secondary building unit (SBU) is a hamburger‐like heptanuclear unit (Zn6CaO30) and these units are interconnected through mbpdc2− carboxylate groups to generate a three‐dimensional framework with the pcu topology. The single net leaves voids that are filled by mutual interpenetration of an independent equivalent framework in a twofold interpenetrating architecture. The title compound shows thermal stability up to 673 K. The excitation and luminescence data showed the emission of a bright‐blue fluorescence. 相似文献
9.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(17):4790-4796
Supported metal nanocrystals have exhibited remarkable catalytic performance in hydrogen generation reactions, which is influenced and even determined by their supports. Accordingly, it is of fundamental importance to determine the direct relationship between catalytic performance and metal–support interactions. Herein, we provide a quantitative profile for exploring metal–support interactions by considering the highest occupied state in single‐atom catalysts. The catalyst studied consisted of isolated Rh atoms dispersed on the surface of VO2 nanorods. It was observed that the activation energy of ammonia–borane hydrolysis changed when the substrate underwent a phase transition. Mechanistic studies indicate that the catalytic performance depended directly on the highest occupied state of the single Rh atoms, which was determined by the band structure of the substrates. Other metal catalysts, even with non‐noble metals, that exhibited significant catalytic activity towards NH3BH3 hydrolysis were rationally designed by adjusting their highest occupied states. 相似文献
10.
Xiao‐Min Hao Gang Chen Chang‐Sheng Gu Ji‐Wei Liu 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(7):712-714
In the title coordination polymer, {[Cd(C6H8O4S)(C13H14N2)]·H2O}n, the CdII atom displays a distorted octahedral coordination, formed by three carboxylate O atoms and one S atom from three different 3,3′‐thiodipropionate ligands, and two N atoms from two different 4,4′‐(propane‐1,3‐diyl)dipyridine ligands. The CdII centres are bridged through carboxylate O atoms of 3,3′‐thiodipropionate ligands and through N atoms of 4,4′‐(propane‐1,3‐diyl)dipyridine ligands to form two different one‐dimensional chains, which intersect to form a two‐dimensional layer. These two‐dimensional layers are linked by S atoms of 3,3′‐thiodipropionate ligands from adjacent layers to form a three‐dimensional network. 相似文献
11.
Yongqiang Zhao Tao Ling Shuangming Chen Bo Jin Anthony Vasileff Yan Jiao Li Song Jun Luo Shi‐Zhang Qiao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(35):12380-12385
Common‐metal‐based single‐atom catalysts (SACs) are quite difficult to design due to the complex synthesis processes required. Herein, we report a single‐atom nickel iodide (SANi‐I) electrocatalyst with atomically dispersed non‐metal iodine atoms. The SANi‐I is prepared via a simple calcination step in a vacuum‐sealed ampoule and subsequent cyclic voltammetry activation. Aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy and synchrotron‐based X‐ray absorption spectroscopy are applied to confirm the atomic‐level dispersion of iodine atoms and detailed structure of SANi‐I. Single iodine atoms are found to be isolated by oxygen atoms. The SANi‐I is structural stable and shows exceptional electrocatalytic activity for the hydrogen evolution reaction (HER). In situ Raman spectroscopy reveals that the hydrogen adatom (Hads) is adsorbed by a single iodine atom, forming the I‐Hads intermediate, which promotes the HER process. 相似文献
12.
Xian‐Fa Zhang Shan Gao Li‐Hua Huo Hui Zhao 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(12):m617-m619
In the title coordination polymer, [Pb(C5H2N2O4)(H2O)]n, the PbII atom is seven‐coordinated by one N atom and five O atoms from four individual imidazole‐4,5‐dicarboxylate (HIDC2−) groups and one water molecule. It is interesting to note that the HIDC2− group serves as a bridging ligand to link the PbII atoms into a three‐dimensional microporous open‐framework. 相似文献
13.
You‐Huan Wei Rui‐Xiang Hu An‐Zhi Tan Zi‐Lu Chen Fu‐Pei Liang 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(10):m453-m455
In the title compound, {[Co(C7H7N2O2)2]·H2O}n, the CoII atom lies on an inversion centre and has octahedral geometry, defined by two O atoms in axial positions and four N atoms in equatorial sites from six different 3,5‐diaminobenzoate ligands. Each 3,5‐diaminobenzoate anion acts as a μ3‐bridging ligand, linking three adjacent CoII ions through one O atom and two N atoms to form a three‐dimensional coordination polymer. 相似文献
14.
Sujittra Youngme Jaturong Phatchimkun Narongsak Chaichit 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(6):m267-m268
In the structure of the title complex, [Cu(C2O4)(C10H9N3)(H2O)]·H2O, the CuII atom displays a square‐pyramidal geometry, being coordinated by two N atoms from the di‐2‐pyridylamine ligand, two O atoms from the oxalate group and one O atom of a water molecule. The complex molecules are linked to form a three‐dimensional supramolecular array by hydrogen‐bonding interactions between coordinated/uncoordinated water molecules and the uncoordinated oxalate O atoms of neighboring molecules. 相似文献
15.
The title compound, [Cu2(C9H10NO3)2(NO3)2(C10H8N2)(H2O)2]n, contains CuII atoms and l ‐tyrosinate (l ‐tyr) and 4,4′‐bipyridine (4,4′‐bipy) ligands in a 2:2:1 ratio. Each Cu atom is coordinated by one amino N atom and two carboxylate O atoms from two l ‐tyr ligands, one N atom from a 4,4′‐bipy ligand, a monodentate nitrate ion and a water molecule in an elongated octahedral geometry. Adjacent Cu atoms are bridged by the bidentate carboxylate groups into a chain. These chains are further linked by the bridging 4,4′‐bipy ligands, forming an undulated chiral two‐dimensional sheet. O—H...O and N—H...O hydrogen bonds connect the sheets in the [100] direction. This study offers useful information for the engineering of chiral coordination polymers with amino acids and 4,4′‐bipy ligands by considering the ratios of the metal ion and organic components. 相似文献
16.
Xiao‐Min Hao Gang Chen Chang‐Sheng Gu Ji‐Wei Liu 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(8):770-772
In the title coordination polymer, [Cd2(SO4)2(C13H8N4)(H2O)2]n, there are two crystallographically independent CdII centres with different coordination geometries. The first CdII centre is hexacoordinated by four O atoms of four sulfate ligands, one water O atom and one N atom of a 1H‐imidazo[4,5‐f][1,10]phenanthroline (IP) ligand, giving a distorted octahedral coordination environment. The second CdII centre is heptacoordinated by four O atoms of three sulfate ligands, one water O atom and two N atoms of one chelating IP ligand, resulting in a distorted monocapped anti‐trigonal prismatic geometry. The symmetry‐independent CdII ions are bridged in an alternating fashion by sulfate ligands, forming one‐dimensional ladder‐like chains which are connected through the IP ligands to form two‐dimensional layers. These two‐dimensional layers are linked by interlayer hydrogen bonds, leading to the formation of a three‐dimensional supramolecular network. 相似文献
17.
A twofold interpenetrating three‐dimensional CdII coordination framework, [Cd(C8H3NO6)(C14H14N4)]n, has been prepared and characterized by IR spectroscopy, elemental analysis, thermal analysis and single‐crystal X‐ray diffraction. The asymmetric unit consists of a divalent CdII atom, one 1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene (1,3‐BMIB) ligand and one fully deprotonated 5‐nitrobenzene‐1,3‐dicarboxylate (NO2‐BDC2−) ligand. The coordination sphere of the CdII atom consists of five O‐donor atoms from three different NO2‐BDC2− ligands and two imidazole N‐donor atoms from two different 1,3‐BMIB ligands, forming a distorted {CdN2O5} pentagonal bipyramid. The NO2‐BDC ligand links three CdII atoms via a μ1‐η1:η1 chelating mode and a μ2‐η2:η1 bridging mode. The title compound is a twofold interpenetrating 3,5‐connected network with the {42.65.83}{42.6} topology. In addition, the compound exhibits fluorescence emissions in the solid state at room temperature. 相似文献
18.
Qiao‐Yun Li Gao‐Wen Yang Rong‐Xin Yuan Jia‐Ping Wang Peng‐Fei Cui 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(1):m26-m29
The CoII atom in bis(5‐aminotetrazole‐1‐acetato)tetraaquacobalt(II), [Co(C3H4N5O2)2(H2O)4], (I), is octahedrally coordinated by six O atoms from two 5‐aminotetrazole‐1‐acetate (atza) ligands and four water molecules. The molecule has a crystallographic centre of symmetry located at the CoII atom. The molecules of (I) are interlinked by hydrogen‐bond interactions, forming a two‐dimensional supramolecular network structure in the ac plane. The CdII atom in catena‐poly[[cadmium(II)]‐bis(μ‐5‐aminotetrazole‐1‐acetato], [Cd(C3H4N5O2)2]n, (II), lies on a twofold axis and is coordinated by two N atoms and four O atoms from four atza ligands to form a distorted octahedral coordination environment. The CdII centres are connected through tridentate atza bridging ligands to form a two‐dimensional layered structure extending along the ab plane, which is further linked into a three‐dimensional structure through hydrogen‐bond interactions. 相似文献
19.
Cheng Tang Yan Jiao Bingyang Shi Jia‐Ning Liu Zhenhua Xie Xiao Chen Qiang Zhang Shi‐Zhang Qiao 《Angewandte Chemie (International ed. in English)》2020,59(23):9171-9176
Single‐atom catalysts (SACs) have great potential in electrocatalysis. Their performance can be rationally optimized by tailoring the metal atoms, adjacent coordinative dopants, and metal loading. However, doing so is still a great challenge because of the limited synthesis approach and insufficient understanding of the structure–property relationships. Herein, we report a new kind of Mo SAC with a unique O,S coordination and a high metal loading over 10 wt %. The isolation and local environment was identified by high‐angle annular dark‐field scanning transmission electron microscopy and extended X‐ray absorption fine structure. The SACs catalyze the oxygen reduction reaction (ORR) via a 2 e? pathway with a high H2O2 selectivity of over 95 % in 0.10 m KOH. The critical role of the Mo single atoms and the coordination structure was revealed by both electrochemical tests and theoretical calculations. 相似文献
20.
Suchada Chantrapromma Anwar Usman Hoong‐Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):m531-m533
In the title compound [systematic name: triaqua(1,4,7,10,13,16‐hexaoxacyclooctadecane‐κ6O)(2‐nitrophenolato‐κO)barium(II)–aqua(1,4,7,10,13,16‐hexaoxacyclooctadecane‐κ6O)‐ bis(2‐nitrophenolato‐κ2O,O′)barium(II)–2‐nitrophenolate (1/1/1)], [Ba(C12H24O6)(C6H4NO3)(H2O)3][Ba(C12H24O6)(C6H4NO3)2(H2O)](C6H4NO3), the two BaII atoms encapsulated by the 18‐crown‐6 rings have different coordinations. Although both BaII atoms are coordinated to the six O atoms of the crowns, in the neutral moiety, the BaII atom is coordinated to one terminal O atom from a water molecule, two phenolate O atoms and two nitro‐group O atoms, while in the cationic moiety, the BaII atom is coordinated to three terminal O atoms from water molecules and one phenolate O atom. Both the crowns are eclipsed and translated along the b direction. In the asymmetric unit, the three components are interconnected by four O—H?O interactions. The packing is stabilized by two intermolecular C—H?O interactions and by one O—H?O interaction. 相似文献