共查询到20条相似文献,搜索用时 46 毫秒
1.
Shinsaku Amano Dimitri Bogdanovski Hisanori Yamane Masami Terauchi Richard Dronskowski 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(5):1684-1689
For the Ti/O system, three titanium monoxide (TiO) phases (α, β, and γ) with defective NaCl‐type structures and a high‐temperature hexagonal phase (H) have been known for decades. In this work, single crystals of a novel polymorph, ɛ‐TiO, were synthesized by using a bismuth flux. X‐ray diffraction (XRD) revealed a hexagonal crystal structure (a=4.9936(3) Å, c=2.8773(2) Å, P 2m) that is isotypic with ɛ‐TaN. While the Ti atoms are surrounded by trigonal prismatic (sixfold coordination) and trigonal planar (threefold coordination) arrangements of O atoms, the O atoms are found in a pseudo‐square‐pyramidal arrangement of Ti atoms. First‐principles calculations of the formation enthalpy and the electron and phonon density of states and crystal orbital Hamilton population (COHP) analysis revealed that ɛ‐TiO is more stable than α‐TiO, which had previously been regarded as the most stable phase at low temperatures. 相似文献
2.
Matthew V. Vollmer Dr. Jing Xie Ryan C. Cammarota Dr. Victor G. Young Jr. Dr. Eckhard Bill Prof. Laura Gagliardi Prof. Connie C. Lu 《Angewandte Chemie (International ed. in English)》2018,57(26):7815-7819
Formal nickelate(?I) complexes bearing Group 13 metalloligands (M=Al and Ga) were isolated. These 17 e? complexes were synthesized by one‐electron reduction of the corresponding Ni0→MIII precursors, and were investigated by single‐crystal X‐ray diffraction, EPR spectroscopy, and quantum chemical calculations. Collectively, the experimental and computational data support: 1) the strengthening of the Ni?M bond upon one‐electron reduction, and 2) the delocalization of the unpaired spin across the Ni and M atoms. An intriguing electronic configuration is revealed where three valence electrons occupy two σ‐type bonding interactions: Ni(3d )2→M and σ‐(Ni?M)1. The latter is an unusual Ni?M σ‐bonding molecular orbital that comprises primarily the Ni 4pz and M npz/ns atomic orbitals. 相似文献
3.
Alexander Ovchinnikov Dr. Matej Bobnar Dr. Yurii Prots Dr. Horst Borrmann Dr. Jörg Sichelschmidt Prof. Yuri Grin Dr. Peter Höhn 《Angewandte Chemie (International ed. in English)》2018,57(36):11579-11583
Two new calcium nitridomanganates, Ca12[Mn19N23] (P3, a=11.81341(3) Å, c=5.58975(2) Å, Z=1) and Ca133[Mn216N260] ( , a=39.477(1) Å, c=5.5974(2) Å, Z=1), were obtained by a gas–solid reaction of Ca3N2 and Mn with N2 at 1273 K and 1223 K, respectively. The crystal structure of Ca12[Mn19N23] was determined from high‐resolution X‐ray synchrotron powder diffraction data, whereas single‐crystal X‐ray diffraction was employed to establish the crystal structure of the Ca133[Mn216N260] phase, which classifies as a complex metallic alloy (CMA). Both crystal structures have 2D nitridomanganate layers containing similar building blocks but of different levels of structural complexity. Bonding analysis as well as magnetic susceptibility and electron spin resonance measurements revealed that only a fraction of the Mn atoms in both structures carries a localized magnetic moment, while for most Mn species the magnetism is quenched as a result of metal–metal bond formation. 相似文献
4.
Shibo Xu Kazutaka Takamatsu Prof. Dr. Koji Hirano Prof. Dr. Masahiro Miura 《Angewandte Chemie (International ed. in English)》2018,57(36):11797-11801
A Ni(OAc)2‐catalyzed C?H coupling of 8‐aminoquinoline‐derived benzamides with epoxides has been developed. The reaction proceeds with concomitant removal of the 8‐aminoquinoline auxiliary to form the corresponding 3,4‐dihydroisocoumarins directly. Additionally, the nickel catalysis is stereospecific, and the cis‐ and trans‐epoxides are converted into the corresponding cis‐ and trans‐dihydroisocoumarins with retention of configuration, which is complementary to previously reported palladium catalysis. Moreover, while still preliminary, the C ?H functionalization is also achieved in the presence of modified NiCl2 catalysts. 相似文献
5.
The β‐Agostic Structure in (C5Me5)2Sc(CH2CH3): Solid‐State NMR Studies of (C5Me5)2Sc−R (R=Me,Ph, Et)
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Damien B. Culver Winn Huynh Dr. Hosein Tafazolian Dr. Ta‐Chung Ong Prof. Dr. Matthew P. Conley 《Angewandte Chemie (International ed. in English)》2018,57(30):9520-9523
Multinuclear solid‐state NMR studies of Cp*2Sc?R (Cp*=pentamethylcyclopentadienyl; R=Me, Ph, Et) and DFT calculations show that the Sc?Et complex contains a β‐CH agostic interaction. The static central transition 45Sc NMR spectra show that the quadrupolar coupling constants (Cq) follow the trend of Ph≈Me>Et, indicating that the Sc?R bond is different in Cp*2Sc?Et compared to the methyl and phenyl complexes. Analysis of the chemical shift tensor (CST) shows that the deshielding experienced by Cβ in Sc?CH2CH3 is related to coupling between the filled σC‐C orbital and the vacant orbital. 相似文献
6.
Catalytic and Atom‐Economic C
−C
Bond Formation: Alkyl Tantalum Ureates for Hydroaminoalkylation
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rebecca C. DiPucchio Dr. Sorin‐Claudiu Roşca Prof. Laurel L. Schafer 《Angewandte Chemie (International ed. in English)》2018,57(13):3469-3472
Atom‐economic and regioselective C ?C bond formation has been achieved by rapid C?H alkylation of unprotected secondary arylamines with unactivated alkenes. The combination of Ta(CH2SiMe3)3Cl2, and a ureate N,O‐chelating‐ligand salt gives catalytic systems prepared in situ that can realize high yields of β‐alkylated aniline derivatives from either terminal or internal alkene substrates. These new catalyst systems realize C?H alkylation in as little as one hour and for the first time a 1:1 stoichiometry of alkene and amine substrates results in high yielding syntheses of isolated amine products by simple filtration and concentration. 相似文献
7.
Manabu Nakaya Wataru Kosaka Hitoshi Miyasaka Yuki Komatsumaru Shogo Kawaguchi Kunihisa Sugimoto Yingjie Zhang Masaaki Nakamura Leonard F. Lindoy Shinya Hayami 《Angewandte Chemie (International ed. in English)》2020,59(26):10658-10665
CO2‐responsive spin‐state conversion between high‐spin (HS) and low‐spin (LS) states at room temperature was achieved in a monomeric cobalt(II) complex. A neutral cobalt(II) complex, [CoII(COO‐terpy)2]?4 H2O ( 1?4 H2O ), stably formed cavities generated via π–π stacking motifs and hydrogen bond networks, resulting in the accommodation of four water molecules. Crystalline 1?4 H2O transformed to solvent‐free 1 without loss of porosity by heating to 420 K. Compound 1 exhibited a selective CO2 adsorption via a gate‐open type of the structural modification. Furthermore, the HS/LS transition temperature (T1/2) was able to be tuned by the CO2 pressure over a wide temperature range. Unlike 1 exhibits the HS state at 290 K, the CO2‐accomodated form 1?CO2 (P =110 kPa) was stabilized in the LS state at 290 K, probably caused by a chemical pressure effect by CO2 accommodation, which provides reversible spin‐state conversion by introducing/evacuating CO2 gas into/from 1 . 相似文献
8.
Water Formation under Silica Thin Films: Real‐Time Observation of a Chemical Reaction in a Physically Confined Space
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Mauricio J. Prieto Dr. Hagen W. Klemm Dr. Feng Xiong Dr. Daniel M. Gottlob Prof. Dr. Dietrich Menzel Dr. Thomas Schmidt Prof. Dr. Hans‐Joachim Freund 《Angewandte Chemie (International ed. in English)》2018,57(28):8749-8753
Using low‐energy electron microscopy and local photoelectron spectroscopy, water formation from adsorbed O and H2 on a Ru(0001) surface covered with a vitreous SiO2 bilayer (BL) was investigated and compared to the same reaction on bare Ru(0001). In both cases the reaction is characterized by moving reaction fronts. The reason for this might be related to the requirement of site release by O adatoms for further H2‐dissociative adsorption. Apparent activation energies ( ) are found for the front motion of 0.59 eV without cover and 0.27 eV under cover. We suggest that the smaller activation energy but higher reaction temperature for the reaction on the SiO2 BL covered Ru(0001) surface is due to a change of the rate‐determining step. Other possible effects of the cover are discussed. Our results give the first values for in confined space. 相似文献
9.
Structure and Composition of the 200 K‐Superconducting Phase of H2S at Ultrahigh Pressure: The Perovskite (SH−)(H3S+)
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof. Dr. Hongjun Xiang Prof. Dr. Annette Bussmann‐Holder Dr. Reinhard K. Kremer Prof. Dr. Arndt Simon Prof. Dr. Jürgen Köhler Prof. Dr. Myung‐Hwan Whangbo 《Angewandte Chemie (International ed. in English)》2016,55(11):3682-3684
At ultrahigh pressure (>110 GPa), H2S is converted into a metallic phase that becomes superconducting with a record Tc of approximately 200 K. It has been proposed that the superconducting phase is body‐centered cubic H3S (Im m, a=3.089 Å) resulting from the decomposition reaction 3 H2S→2 H3S+S. The analogy between H2S and H2O led us to a very different conclusion. The well‐known dissociation of water into H3O+ and OH? increases by orders of magnitude under pressure. H2S is anticipated to behave similarly under pressure, with the dissociation process 2 H2S→H3S++SH? leading to the perovskite structure (SH?)(H3S+). This phase consists of corner‐sharing SH6 octahedra with SH? ions at each A site (the centers of the S8 cubes). DFT calculations show that the perovskite (SH?)(H3S+) is thermodynamically more stable than the Im m structure of H3S, and suggest that the A site hydrogen atoms are most likely fluxional even at Tc . 相似文献
10.
Fangfang Jian Ying Wang Lude Lu Xujie Yang Xin Wang Suchada Chantrapromma Hoong‐Kun Fun Ibrahim Abdul Razak 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):714-716
The crystal structures of tris(2‐methylquinolin‐8‐olato‐N,O)iron(III), [Fe(C10H8NO)3], (I), and aquabis(2‐methylquinolin‐8‐olato‐N,O)copper(II), [Cu(C10H8NO)2(H2O)], (II), have been determined. Compound (I) has a distorted octahedral configuration, in which the central Fe atom is coordinated by three N atoms and three O atoms from three 2‐methylquinolin‐8‐olate ligands. The three Fe—O bond distances are in the range 1.934 (2)–1.947 (2) Å, while the three Fe—N bond distances range from 2.204 (2) to 2.405 (2) Å. In compound (II), the central CuII atom and H2O group lie on the crystallographic twofold axis and the coordination geometry of the CuII atom is close to trigonal bipyramidal, with the three O atoms in the basal plane and the two N atoms in apical positions. The Cu—N bond length is 2.018 (5) Å. The Cu—O bond length in the basal positions is 1.991 (4) Å, while the Cu—O bond length in the apical position is 2.273 (6) Å. There is an intermolecular OW—H?O hydrogen bond which links the molecules into a linear chain along the b axis. 相似文献
11.
Nitrogen‐Doped Ordered Mesoporous Carbon Supported Bimetallic PtCo Nanoparticles for Upgrading of Biophenolics
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Guang‐Hui Wang Dr. Zhengwen Cao Dr. Dong Gu Norbert Pfänder Ann‐Christin Swertz Bernd Spliethoff Hans‐Josef Bongard Dr. Claudia Weidenthaler Dr. Wolfgang Schmidt Dr. Roberto Rinaldi Prof. Dr. Ferdi Schüth 《Angewandte Chemie (International ed. in English)》2016,55(31):8850-8855
Hydrodeoxygenation (HDO) is an attractive route for the upgrading of bio‐oils produced from lignocellulose. Current catalysts require harsh conditions to effect HDO, decreasing the process efficiency in terms of energy and carbon balance. Herein we report a novel and facile method for synthesizing bimetallic PtCo nanoparticle catalysts (ca. 1.5 nm) highly dispersed in the framework of nitrogen‐doped ordered mesoporous carbon (NOMC) for this reaction. We demonstrate that NOMC with either 2D hexagonal (p6m) or 3D cubic (Im m) structure can be easily synthesized by simply adjusting the polymerization temperature. We also demonstrate that PtCo/NOMC (metal loading: Pt 9.90 wt %; Co 3.31 wt %) is a highly effective catalyst for HDO of phenolic compounds and “real‐world” biomass‐derived phenolic streams. In the presence of PtCo/NOMC, full deoxygenation of phenolic compounds and a biomass‐derived phenolic stream is achieved under conditions of low severity. 相似文献
12.
Biju Basumatary Ikuho Hashiguchi Shigeki Mori Soji Shimizu Masatoshi Ishida Hiroyuki Furuta 《Angewandte Chemie (International ed. in English)》2020,59(37):15897-15901
A copper complex of a heterocorrole analogue with an N–N linkage, 1,19‐diaza‐21,24‐dicarbadibenzocorrole ( Cu‐5 ), was successfully synthesized via oxidative metalation–cyclization of a tetrapyrrolic precursor. The N–N linkage in the skeleton of Cu‐5 , which serves as a mediator of π‐electron delocalization, features an 18π aromatic system. The electronic structure of Cu‐5 is best described as a ground‐state singlet species stabilized by the distinct NNCC coordination core. This finding shows how the ligand's design can be used to modulate the Cu orbital energy, thereby making such compounds invaluable for copper‐based catalytic applications. 相似文献
13.
Lesaw Siero Maria Bukowska‐Strzyewska 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):19-21
In the title dimeric complex, [Cu2(C4H4O4)2(C7H6N2S)4], which possesses a centre of symmetry, the Cu atoms are enclosed in a 14‐membered ring. They adopt a distorted square‐bipyramidal (4+2) coordination. The four closest donor atoms are two N atoms of 2‐aminobenzothiazole ligands and two O atoms of the succinate carboxylate groups. They form a square‐planar cis arrangement, with an average Cu—N distance of 2.003 (3) Å and Cu—O distances of 1.949 (3) and 1.965 (3) Å. Two longer Cu—O bonds of 2.709 (3) and 2.613 (3) Å involving the remaining O atoms of the carboxylate groups complete the sixfold coordination of the Cu atoms. The H atoms of each amino group of the 2‐aminobenzothiazole molecules form intra‐ and intermolecular N—H?O hydrogen bonds. A nearly perpendicular intermolecular C—H?Cg interaction (Cg is the centroid of the imidazole ring) is observed. The intramolecular Cu?Cu distance is 6.384 (2) Å. 相似文献
14.
Cornelis Lensink Graeme J. Gainsford Menno J. R. Brandsma 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):m529-m530
The title compound, [Ti(C15H17NO2S)Cl2], has a Ti atom bound to the N and O atoms of a p‐toluenesulfonamide ligand, which is tethered by a three‐carbon chain to a η5‐cyclopentadienyl group. The distorted square‐pyramidal geometry is completed by two Cl atoms. The Ti—N bond length of 2.0375 (13) Å is longer than that in related compounds, the N atom having asymmetric trigonal–planar geometry. Conformational strain relief is noted when compared with ethyl‐tethered compounds. 相似文献
15.
Ligand‐Enabled Enantioselective C
–H Activation of Tetrahydroquinolines and Saturated Aza‐Heterocycles by RhI
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
《Angewandte Chemie (International ed. in English)》2018,57(31):9950-9954
The first rhodium(I)‐catalyzed enantioselective intermolecular C –H activation of various saturated aza‐heterocycles including tetrahydroquinolines, piperidines, piperazines, azetidines, pyrrolidines, and azepanes is presented. The combination of a rhodium(I) precatalyst and a chiral monodentate phosphonite ligand is shown to be a powerful catalytic system to access a variety of important enantio‐enriched heterocycles from simple starting materials. Notably, the C –H activation of tetrahydroquinolines is especially challenging due to the adjacent C −H bond. This redox‐neutral methodology provides a new synthetic route to α‐N‐arylated heterocycles with high chemoselectivity and enantioselectivity up to 97 % ee. 相似文献
16.
Zhixing Lin Dr. Shaohua Liu Wenting Mao Hao Tian Nan Wang Ninghe Zhang Dr. Feng Tian Prof. Lu Han Prof. Xinliang Feng Prof. Yiyong Mai 《Angewandte Chemie (International ed. in English)》2017,56(25):7135-7140
We herein report the tunable self-assembly of simple block copolymers, namely polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers, into porous cubosomes with inverse or mesophases of controlled unit cell parameters as well as hexasomes with an inverse hexagonal (p6mm) structure, which have been rarely observed in polymer self-assembly. A new morphological phase diagram was constructed for the solution self-assembly of PS-b-PEO based on the volume fraction of the PS block against the initial copolymer concentration. The formation mechanisms of the cubosomes and hexasomes have also been revealed. This study not only affords a simple system for the controllable preparation and fundamental studies of ordered bicontinuous structures, but also opens up a new avenue towards porous architectures with highly ordered pores. 相似文献
17.
Masood Parvez Saqib Ali Sajjad Ahmad Moazzam Hussain Bhatti Muhammad Mazhar 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):m334-m335
The crystal structure of catena‐poly[[tri‐n‐butyltin]‐μ‐3‐(1‐naphthylaminocarbonyl)acrylato‐κ2O1:O3], [Sn(C4H9)3(C14H10NO3)]n, is composed of polymeric chains wherein the metal center exhibits a distorted trigonal‐bipyramidal geometry, with three n‐butyl groups defining the trigonal plane [mean Sn—C 2.133 (7) Å] and the axial positions being occupied by the carboxylate O atoms of two different N‐(1‐naphthyl)maleamate ligands with inequivalent Sn—O distances [2.167 (4) and 2.457 (4) Å]. The N‐(1‐naphthyl)maleamate fragment forms an essentially planar seven‐membered ring involving an intramolecular N—H?O hydrogen bond. 相似文献
18.
Lei Ji Lei Li Xuqiang Ji Ya Zhang Shiyong Mou Tongwei Wu Qian Liu Baihai Li Xiaojuan Zhu Yonglan Luo Xifeng Shi Abdullah M. Asiri Xuping Sun 《Angewandte Chemie (International ed. in English)》2020,59(2):758-762
Electrochemical reduction of CO2 into various chemicals and fuels provides an attractive pathway for environmental and energy sustainability. It is now shown that a FeP nanoarray on Ti mesh (FeP NA/TM) acts as an efficient 3D catalyst electrode for the CO2 reduction reaction to convert CO2 into alcohols with high selectivity. In 0.5 m KHCO3, such FeP NA/TM is capable of achieving a high Faradaic efficiency (FE ) up to 80.2 %, with a total FE of 94.3 % at ?0.20 V vs. reversible hydrogen electrode. Density functional theory calculations reveal that the FeP(211) surface significantly promotes the adsorption and reduction of CO2 toward CH3OH owing to the synergistic effect of two adjacent Fe atoms, and the potential‐determining step is the hydrogenation process of *CO. 相似文献
19.
Syntheses and Structures of the Titanium(III) Siloxanes [Ti(OSiPh3)3(thf)2] and [Ti(OSiPh3)3(py)2] The new titaniumtrioxysilanes [Ti(OSiPh3)3(thf)2] ( 1 ) and [Ti(OSiPh3)3(py)2] ( 2 ) have been obtained from the reaction of titaniumtrichloride with LiOSiPh3 in the presence of the corresponding bases tetrahydrofurane (thf) and pyridine (py). From the crystal structures of both compounds it is evident that the titanium atoms are in the centres of trigonal‐bipyramidal coordination figures, with the donor atoms in axial positions. The compounds 1 and 2 have slightly different structures (mean values: 1 : Ti‐O(Si) 1.897(9), Ti‐O(C) 2.136(8) Å; 2 : Ti‐O 1.902(9), Ti‐N2.252(8) Å) and have a single absorption band in the visible region of the UV‐spectrum. The exchange of the thf‐ligands in 1 by pyridine (in high molar excess) seems to be hindered as deduced from UV‐spectroscopy. 相似文献
20.
Dr. Allison M. Latshaw Dr. W. Michael Chance Dr. Gregory Morrison Karl D. zur Loye Branford O. Wilkins Mark D. Smith Dr. Pamela S. Whitfield Dr. Melanie J. Kirkham Dr. Sebastian A. Stoian Prof. Dr. Hans‐Conrad zur Loye 《Angewandte Chemie (International ed. in English)》2016,55(42):13195-13199
Crystals of the first sodalite‐type zeolite containing an all‐iron framework, a ferrolite, Ba8(Fe12O24)Nay(OH)6?x H2O, were synthesized using the hydroflux method in nearly quantitative yield. Ba8(Fe12O24)Nay(OH)6?x H2O crystallizes in the cubic space group with a=10.0476(1) Å. Slightly distorted FeO4 tetrahedra are linked to form Fe4O4 and Fe6O6 rings, which in turn yield channels and internal cavities that are characteristic of the sodalite structure. Barium, sodium, and hydroxide ions and water molecules are found in the channels and provide charge balance. Magnetic measurements indicate that the ferrolite exhibits magnetic order up to at least 700 K, with the field‐cooled and zero‐field‐cooled curves diverging. Analysis of the 57Fe Mössbauer spectra revealed two spectral components that have equal spectral areas, indicating the presence of two subsets of iron centers in the structure. Dehydrated versions of the ferrolite were also prepared by heating the sample. 相似文献