Erste strukturelle Charakterisierung eines leicht oxidierbaren 1,4-Dihydrochinoxalin-Derivats / First Structural Characterization of an Easily Oxidized Derivative of 1,4-Dihydroquinoxaline

1993 ◽  
Vol 48 (6) ◽  
pp. 713-718 ◽  
Author(s):  
Alexander Lichtblau ◽  
Hans-Dieter Hausen ◽  
Wolfgang Kaim
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Dihedral Angle ◽  
Structural Characterization ◽  
Crystal Structure Analysis ◽  
Ring System ◽  
Structural Flexibility ◽  
Steric Repulsion ◽  
Alkyl Groups

The first crystal structure analysis of a 1,4-dihydroquinoxaline is described by example of the 1,4-bis(tert-butyldimethylsilyl) derivative. In the solid state, this molecule exhibits a nonplanar heterocycle with a dihedral angle of 156.3° along the N—N axis in the boat-shaped 8π electron ring system. The alkyl groups of the Si(tert-Bu)Me2 substituents are arranged as to minimize steric repulsion. Despite the reduced π electron conjugation due to non-planarity, the compound is oxidized reversibly to an EPR detectable radical cation at —0.59 V vs. ferrocene in dichloromethane. However, the second oxidation to the fully aromatic dication is electrochemically irreversible. A comparison with previously obtained results illustrates the structural flexibility of the non-aromatic 1,4-dihydro-1,4-diazine ring system which is strongly affected by rather weak non-bonded interactions.

Synthesis and structural characterization of Li3Y(BO3)2

2017 ◽  
Vol 72 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Sebastian Bräuchle ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Solid State ◽  
Boric Acid ◽  
Structural Characterization ◽  
Diffraction Data ◽  
Lithium Carbonate ◽  
X Ray Diffraction ◽  
X Ray

AbstractLi3Y(BO3)2 was prepared by high-temperature solid state synthesis at 900°C in a platinum crucible from lithium carbonate, boric acid, and yttrium(III) oxide. The compound crystallizes monoclinically in the space group P21/c (no. 14) (Z=4) isotypically to Li3Gd(BO3)2. The structure was refined from single-crystal X-ray diffraction data: a=8.616(3), b=6.416(3), c=10.014(2) Å, β=116.6(2)°, V=494.9(3) Å3, R1=0.0211, and wR2=0.0378 for all data. The crystal structure of Li3Y(BO3)2 consists of [Y2O14] dinuclear units, which are interconnected to each other by planar B(1)O3 groups and LiO4 tetrahedra via common edges and corners along the a axis.

Generation and Structural Characterization of an [(Imidazol-2-ylidene)HfCl5]-Anion/Imidazolium Cation Salt

2003 ◽  
Vol 58 (10) ◽  
pp. 1005-1008 ◽  
Author(s):  
Martin Niehues ◽  
Gerald Kehr ◽  
Roland Fröhlich ◽  
Gerhard Erker
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Structural Characterization ◽  
Crystal Structure Analysis ◽  
Chloride Anion ◽  
Imidazolium Cation ◽  
X Ray ◽  
Hafnium Tetrachloride

The reaction of 1,3-diisopropylimidazolium chloride (3) with benzylpotassium in d5-bromobenzene generates the stable carbene 1,3-diisopropylimidazol-2-ylidene that is trapped by hafnium tetrachloride. A chloride anion is subsequently added to the Hf atom of the resulting intermediate to yield the salt [(1,3-diisopropylimidazol-2-ylidene)HfCl₅−][1,3-diisopropylimidazolium+] 6 that was characterized by an X-ray crystal structure analysis.

Structural characterization of Cd3(O3PC2H4CO2)2·2H2O from in-house X-ray powder data and NMR

2005 ◽  
Vol 61 (6) ◽  
pp. 669-674 ◽  
Author(s):  
Naima Bestaoui ◽  
Xiang Ouyang ◽  
Florence Fredoueil ◽  
Bruno Bujoli ◽  
Abraham Clearfield
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Structural Characterization ◽  
Title Compound ◽  
Solid State Nmr ◽  
Hydrothermal Reaction ◽  
X Ray ◽  
Space Groups ◽  
Nmr Data

The title compound poly[[bis(μ-2-carboxylatoethylphosphonato)cadmium] dihydrate], Cd3(O3PC2H4CO2)2·2H2O, was prepared by a hydrothermal reaction and its crystal structure determined from in-house powder data. The structure was solved in both P21/c and P21 space groups. The refinement converged with Rp = 0.1046, R wp = 0.1378 and Rf = 0.0763 in P21/c. However, the solid-state NMR data could not be explained. The structure was then solved in P21 and the refinement converged with Rp = 0.0750, R wp = 0.1022 and Rf = 0.0409 and satisfied the NMR requirements.

scholarly journals Crystal Structure of Ruthenium Phthalocyanine with Diaxial Monoatomic Ligand: Bis(Triphenylphosphine)Iminium Dichloro(Phthalocyaninato(2-))Ruthenium(III)

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Derrick Ethelbhert Yu ◽  
Akira Kikuchi ◽  
Tetsuya Taketsugu ◽  
Tamotsu Inabe
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Ab Initio ◽  
Structural Characterization ◽  
Theoretical Calculations ◽  
Molecular Conductors ◽  
X Ray ◽  
Phthalocyanine Complex ◽  
Axial Ligands

Axially-ligated iron phthalocyanines have been found to be good molecular conductors with giant negative magnetoresistance (GNMR) which originates from a strong intramolecularπ-dinteraction between the metal and phthalocyanine. Ab initio theoretical calculations showed that substitution of ruthenium into the phthalocyanine complex would result in a significant increase in theπ-dinteraction of the system, potentially intensifying GNMR. This paper presents the crystal preparation and X-ray structural characterization of bis(triphenylphosphine)iminium dichloro(phthalocyaninato(2-))ruthenium(III), PNP [RuIII(Pc2−)Cl2]. It is observed that [RuIII(Pc2−)Cl2] system has a symmetric planar RuPc unit with perpendicular axial ligands which results in a unidirectional and uniform solid-state arrangement, suitable forπ-dinteraction-based molecular conductors with potentially exceptional GNMR.

Crystal structure analysis of 4-R-phenyl-2,6-dimethyl-3,5-N-(dimethylcarbamoyl)-1,4-dihydropyridines [R=2-nitro (1), 4-methoxy (2) and 3,4-dichloro (3)]

1998 ◽  
Vol 213 (3) ◽  
Author(s):  
M. Bidya Sagar ◽  
K. Ravikumar ◽  
Y. S. Sadanandam
Keyword(s):  
Crystal Structure ◽  
Calcium Channel ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Calcium Channel Antagonists

AbstractThe crystallographic characterization of the following three calcium channel antagonists is reported here: 2,6-dimethyl-3,5-dicarbamoyl-4-[2-nitro]-1,4-dihydropyridine (

scholarly journals Crystal structure of 5,10,15-triphenyl-20-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)porphyrin

2014 ◽  
Vol 70 (10) ◽  
pp. o1085-o1086
Author(s):  
Mathias O. Senge ◽  
Hans-Georg Eckhardt
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Central Region ◽  
Title Compound ◽  
Ring System ◽  
Compound C ◽  
Porphyrin Macrocycle ◽  
Phenyl Rings ◽  
Supramolecular Chains

In the title compound, C44H37BN4O2, the dihedral angle between the plane of the porphyrin macrocycle ring system [r.m.s. deviation = 0.159 (1) Å] and those of three phenyl rings are 66.11 (4), 74.75 (4) and 57.00 (4)°. The conformational distortion is characterized by a mixture of ruffled, saddle and in-plane distortion modes. In the crystal, the porphyrin molecules are linked by C—H...π interactions into supramolecular chains running along thea-axis direction. A pair of bifurcated N—H...(N,N) hydrogen bonds occur across the central region of the macrocycle.

scholarly journals KCTD proteins as Cullin3 E3 Ligase adapters

2014 ◽  
Vol 70 (a1) ◽  
pp. C305-C305
Author(s):  
Alan Ji ◽  
Gilbert Privé
Keyword(s):  
Crystal Structure ◽  
Structural Characterization ◽  
Dissociation Constants ◽  
E3 Ligase ◽  
Terminal Region ◽  
Btb Domain ◽  
Substrate Protein ◽  
Ubiquitin E3 Ligase ◽  
Ubiquitin Moiety

Cullin3 (Cul3) is an ubiquitin E3 ligase responsible for catalyzing the transfer of an ubiquitin moiety from an E2 enzyme to a target substrate protein. The C-terminal region of Cul3 binds RBX1/E2-ubiquitin, while, the N-terminal region interacts with various BTB domain proteins which serve as substrate adaptors. Previously, our group determined the crystal structures of the homodimeric BTB proteins SPOP and KLHL3 in complex with the N-terminal domain of Cul3, revealing the determinants responsible for the BTB/Cul3 interaction [1, 2]. A second class of BTB-domain containing proteins, the KCTD proteins, are also Cul3 substrate adaptors but these do not share many of the previously determined features for Cul3 binding. Furthermore, KCTD proteins form homotetramers and homopentamers via BTB oligomerization rather than the previously described homodimers. Despite these differences, many KCTD proteins interact with Cul3 with dissociation constants of approximately 50 nM. While the target substrates for many of the KCTD/Cul3 E3 ligase complexes are unknown, recent studies have implicated the GABAβ2 receptor as an interactor of KCTD 8, 12, 12b and 16. Here, we report the pentameric crystal structure of the KCTD9 BTB domain and our progress on the structural characterization of Cul3/KCTD/substrate complexes.

A Methyl Group Bridging on Three Metal Atoms. Solid-State and Solution Structural Characterization of the [Re3(μ-H)3(μ3-CH3)(CO)9]-Anion

1999 ◽  
Vol 121 (10) ◽  
pp. 2307-2308 ◽  
Author(s):  
T. Beringhelli ◽  
G. D'Alfonso ◽  
M. Panigati ◽  
F. Porta ◽  
P. Mercandelli ◽  
...  
Keyword(s):  
Solid State ◽  
Structural Characterization ◽  
Methyl Group ◽  
Metal Atoms
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