共查询到20条相似文献,搜索用时 31 毫秒
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Prof. Dr. Sjoerd Harder Dominik Naglav Dr. Christian Ruspic Prof. Dr. Claudia Wickleder Dr. Matthias Adlung Dr. Wilfried Hermes Dr. Matthias Eul Prof. Dr. Rainer Pöttgen Dr. Daniel B. Rego Prof. Dr. Frederic Poineau Prof. Dr. Kenneth R. Czerwinski Prof. Dr. Rolfe H. Herber Prof. Dr. Israel Nowik 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(37):12272-12280
The superbulky deca‐aryleuropocene [Eu(CpBIG)2], CpBIG=(4‐nBu‐C6H4)5‐cyclopentadienyl, was prepared by reaction of [Eu(dmat)2(thf)2], DMAT=2‐Me2N‐α‐Me3Si‐benzyl, with two equivalents of CpBIGH. Recrystallizyation from cold hexane gave the product with a surprisingly bright and efficient orange emission (45 % quantum yield). The crystal structure is isomorphic to those of [M(CpBIG)2] (M=Sm, Yb, Ca, Ba) and shows the typical distortions that arise from CpBIG???CpBIG attraction as well as excessively large displacement parameter for the heavy Eu atom (Ueq=0.075). In order to gain information on the true oxidation state of the central metal in superbulky metallocenes [M(CpBIG)2] (M=Sm, Eu, Yb), several physical analyses have been applied. Temperature‐dependent magnetic susceptibility data of [Yb(CpBIG)2] show diamagnetism, indicating stable divalent ytterbium. Temperature‐dependent 151Eu Mössbauer effect spectroscopic examination of [Eu(CpBIG)2] was examined over the temperature range 93–215 K and the hyperfine and dynamical properties of the EuII species are discussed in detail. The mean square amplitude of vibration of the Eu atom as a function of temperature was determined and compared to the value extracted from the single‐crystal X‐ray data at 203 K. The large difference in these two values was ascribed to the presence of static disorder and/or the presence of low‐frequency torsional and librational modes in [Eu(CpBIG)2]. X‐ray absorbance near edge spectroscopy (XANES) showed that all three [Ln(CpBIG)2] (Ln=Sm, Eu, Yb) compounds are divalent. The XANES white‐line spectra are at 8.3, 7.3, and 7.8 eV, for Sm, Eu, and Yb, respectively, lower than the Ln2O3 standards. No XANES temperature dependence was found from room temperature to 100 K. XANES also showed that the [Ln(CpBIG)2] complexes had less trivalent impurity than a [EuI2(thf)x] standard. The complex [Eu(CpBIG)2] shows already at room temperature strong orange photoluminescence (quantum yield: 45 %): excitation at 412 nm (24270 cm?1) gives a symmetrical single band in the emission spectrum at 606 nm (νmax=16495 cm?1, FWHM: 2090 cm?1, Stokes‐shift: 2140 cm?1), which is assigned to a 4f65d1→4f7 transition of EuII. These remarkable values compare well to those for EuII‐doped ionic host lattices and are likely caused by the rigidity of the [Eu(CpBIG)2] complex. Sharp emission signals, typical for EuIII, are not visible. 相似文献
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Christopher S. Frampton David D. MacNicol Derek R. Wilson 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(5):o188-o191
The title compounds, C18H21NO and C18H21NS, in their enantiomerically pure forms are isostructural with the enantiomerically pure 4‐(4‐hydroxyphenyl)‐2,2,4‐trimethylchroman and 4‐(2,4‐dihydroxyphenyl)‐2,2,4‐trimethylchroman analogues and form extended linear chains via N—H...O or N—H...S hydrogen bonding along the [100] direction. The absolute configuration for both compounds was determined by anomalous dispersion methods with reference to both the Flack parameter and, for the light‐atom compound, Bayesian statistics on Bijvoet differences. 相似文献
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Xinjiang Huang Genevieve H. Kuhn Vladimir N. Nesterov Boris B. Averkiev Benjamin Penn Mikhail Yu. Antipin Tatiana V. Timofeeva 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):o624-o628
Syntheses and X‐ray structural investigations have been carried out for (E)‐(4‐hydroxyphenyl)(4‐nitrophenyl)diazene, C12H9N3O3, (Ia), (E)‐(4‐methoxyphenyl)(4‐nitrophenyl)diazene, C13H11N3O3, (IIIa), and (E)‐[4‐(6‐bromohexyloxy)phenyl](4‐cyanophenyl)diazene, C19H20BrN3O, (IIIc). In all of these compounds, the molecules are almost planar and the azobenzene core has a trans geometry. Compound (Ia) contains four and compound (IIIc) contains two independent molecules in the asymmetric unit, both in space group P (No. 2). In compound (Ia), the independent molecules are almost identical, whereas in crystal (IIIc), the two independent molecules differ significantly due to different conformations of the alkyl tails. In the crystals of (Ia) and (IIIa), the molecules are arranged in almost planar sheets. In the crystal of (IIIc), the molecules are packed with a marked separation of the azobenzene cores and alkyl tails, which is common for the solid crystalline precursors of mesogens. 相似文献
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Ashokkumar Subashini Kandasamy Ramamurthi Helen Stoeckli‐Evans 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(10):o408-o412
The 4‐chloro‐ [C14H11ClN2O2, (I)], 4‐bromo‐ [C14H10BrN2O2, (II)] and 4‐diethylamino‐ [C18H21N3O2, (III)] derivatives of benzylidene‐4‐hydroxybenzohydrazide, all crystallize in the same space group (P21/c), (I) and (II) also being isomorphous. In all three compounds, the conformation about the C=N bond is E. The molecules of (I) and (II) are relatively planar, with dihedral angles between the two benzene rings of 5.75 (12) and 9.81 (17)°, respectively. In (III), however, the same angle is 77.27 (9)°. In the crystal structures of (I) and (II), two‐dimensional slab‐like networks extending in the a and c directions are formed via N—H...O and O—H...O hydrogen bonds. The molecules stack head‐to‐tail viaπ–π interactions involving the aromatic rings [centroid–centroid distance = 3.7622 (14) Å in (I) and 3.8021 (19) Å in (II)]. In (III), undulating two‐dimensional networks extending in the b and c directions are formed via N—H...O and O—H...O hydrogen bonds. The molecules stack head‐to‐head viaπ–π interactions involving inversion‐related benzene rings [centroid–centroid distances = 3.6977 (12) and 3.8368 (11) Å]. 相似文献
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Hartmut Fuess Michaela Schwarz Erich F. Paulus Jens Hartung Ingrid Svoboda 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(7):o386-o388
The title compound, C20H18ClNOS2, is a thiazole‐derived thiohydroxamic acid O‐ester. The value of Z′ is 3 and the asymmetric unit comprises three molecules of identical helicity along the N—O bond. Two of these show an anti and the third a syn arrangement of substituents attached in positions 3 and 4 to the 1,3‐thiazole nucleus. 相似文献
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Jií Ludvík Jií Urban Jan Fbry Ivana Císaov 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(4):o259-o262
The title structures, both C10H10N4O, are substitutional isomers. The N—N bond lengths are longer and the C=N bond lengths are shorter by ca 0.025 Å than the respective average values in the C=N—N=C group of asymmetric triazines; the assessed respective bond orders are 1.3 and 1.7. There are N—H⋯O and N—H⋯N hydrogen bonds in both structures, with 4‐amino‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one containing a rare bifurcated N—H⋯N,N hydrogen bond. The structures differ in their molecular stacking and the hydrogen‐bonding patterns. 相似文献
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Hasan Kocaokutgen Mahmut Gür Ibrahim Uar Sevil
zknal Orhan Büyükgüngr 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(2):o111-o113
The crystal structures of the title compounds, C17H15BrN2O2, (I), and C18H18N2O2, (II), determined at room temperature, have a trans configuration with respect to the diazene linkage, as found for other azo (diazene) derivatives. The aromatic mean planes are nearly coplanar, with a dihedral angle between these planes of 8.31 (2)° for (I) and 3.74 (2)° for (II). In both complexes, the mean plane of the ester group is nearly perpendicular to the aromatic ring planes. In both compounds, the crystal packing involves only π–π and π–ring interactions, which combine to stabilize the extended structure. 相似文献
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G. Prochniak V. Videnova‐Adrabinska 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(8):m287-m290
This study presents the coordination modes and crystal organization of a calcium–potassium coordination polymer, poly[hexaaquabis(μ4‐4‐carboxybenzenesulfonato‐κ4O1:O1′:O1′′:O4)bis(μ3‐4‐carboxybenzenesulfonato‐κ2O1:O1′)calcium(II)dipotassium(I)], [CaK2(C7H5O5S)4(H2O)6]n, displaying a novel two‐dimensional framework. The potassium ion is seven‐coordinated by four sulfonate and one carboxyl O atom located on five different acid ligands, two of which are unique, and by two symmetry‐independent water O atoms. A pair of close potassium ions share two inversion‐related sulfonate O‐atom sites to form a dimeric K2O12 unit, which is extended into a one‐dimensional array along the a‐axis direction. The six‐coordinate Ca2+ ion occupies a special position () at (0, , ) and is surrounded by four sulfonate O atoms from two inversion‐related pairs of unique acid monoanions and by two O atoms from aqua ligands. The compound displays a layered structure, with K2O12 and CaO6 polyhedra in the layers and aromatic linkers between the layers. The three‐dimensional scaffold is open, with nano‐sized channels along the c axis. 相似文献
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Susanne Flock Clemens Bruhn Heinrich Fink Herbert Frauenrath 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(2):o101-o103
The title enantiomorphic compounds, C16H23NO4S, have been obtained in an enantiomerically pure form by crystallization from a diastereomeric mixture either of (2S,4S)‐ and (2R,4S)‐ or of (2R,4R)‐ and (2S,4R)‐2‐tert‐butyl‐4‐methyl‐3‐(4‐tolylsulfonyl)‐1,3‐oxazolidine‐4‐carbaldehyde. These mixtures were prepared by an aziridination rearrangement process starting with (S)‐ or (R)‐2‐tert‐butyl‐5‐methyl‐4H‐1,3‐dioxine. The crystal structures indicate an envelope conformation of the oxazolidine moiety for both compounds. 相似文献
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Alberto Insuasty Braulio Insuasty Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(1):74-76
The molecules of the title compound, C17H21N3OS, are characterized by a wide C—C—C angle at the methine C atom linking the aryl and thiazolidine rings, associated with a short repulsive intramolecular S...H contact between atoms in these two rings. A single piperidine–arene C—H...π hydrogen bond links pairs of molecules into centrosymmetric dimers. 相似文献
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Krzysztof Ejsmont Agnieszka Kudelko Wojciech Zieliski 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(3):o141-o143
The racemic title compound, C17H23N3O3, isolated from the reaction of l ‐(−)‐tyrosine hydrazide with triethyl orthopropionate in the presence of a catalytic quantity of p‐toluenesulfonic acid (p‐TsOH), crystallizes with Z′ = 1 in a centrosymmetric monoclinic unit cell. The molecule contains two planar fragments, viz. the benzene and imidazole rings, linked by two C—C single bonds. The dihedral angle between the two planes is 59.54 (5)° and the molecule adopts a synclinal conformation. The HOMA (harmonic oscillator model of aromaticity) index, calculated for the benzene ring, demonstrates no substantial interaction between the two π‐electron delocalization regions in the molecule. In the crystal structure, there is an O—H...N hydrogen bond that links the molecules along the c axis. 相似文献
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Vladimir N. Nesterov 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):o806-o809
In the title compound 3,5‐bis(4‐methoxybenzylidene)‐1‐methyl‐4‐piperidone, C22H23NO3, (I), the central heterocyclic ring adopts a flattened boat conformation, while in the related salt 3,5‐bis(4‐methoxybenzylidene)‐1‐methyl‐4‐oxopiperidinium chloride, C22H24NO3+·Cl−, (II), the ring exhibits a `sofa' conformation in which the N atom deviates from the planar fragment. The pendant benzene rings are twisted from the heterocyclic ring planes in both molecules in the same direction, the range of dihedral angles between the ring planes being 24.5 (2)–32.7 (2)°. The dominant packing motif in (I) involves centrosymmetric dimers bound by weak intermolecular C—H⋯O hydrogen bonds. In (II), cations and anions are linked by strong N—H⋯Cl hydrogen bonds, while weak C—H⋯O and C—H⋯Cl hydrogen bonds link the cations and anions into a three‐dimensional framework. 相似文献
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Xue‐Qin Cao Zhan‐Xiong Li Guo‐Qiang Chen De‐Chun Zhang 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(11):o671-o672
The title molecule, C9H10N4O3, consists of benzene and imidazole rings which are almost perpendicular to each other. A hydroxyimino group is directly linked to the imidazole ring with a double C=N bond, which is the first example in this type of compound. The double bond may be a good location for the initiation of various reactions with a wide range of potential applications. In the crystal structure, there are π–π interactions between molecules related by a centre of symmetry, with the imidazole and benzene rings almost completely overlapped. The molecules are hydrogen bonded in each direction and form a three‐dimensional hydrogen‐bond network. 相似文献