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1.
Peter Schwendt Michal Sivák Andrey E. Lapshin Yury I. Smolin Yury F. Shepelev Dalma Gyepesov 《Transition Metal Chemistry》1994,19(1):34-36
Summary The monoperoxo complexes, M2[VO(HEDTA)(O2)]· 4H2O, where M is K+ or NH
4
+
and H4EDTA is ethylene-diaminetetraacetic acid, were prepared and characterized by Raman and i.r. spectra in the solid state and in aqueous solution. The single crystal X-ray study revealed a pentagonal bipyramidal anion structure with a tetradentate HEDTA(3—) ligand. The decomposition of complexes in aqueous solution to blue vanadium(IV) complexes as end products proceeds via a nonperoxo complex of vanadium. 相似文献
2.
Vratislav Langer Dalma Gyepesov Jozef Lusto Juraj Kronek Eva Scholtzov Miroslav Ko 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(7):o416-o418
In the crystal structure of the title compound, C11H13NO2, there are strong intermolecular O—H⋯N hydrogen bonds which, together with weak intramolecular C—H⋯O hydrogen bonds, lead to the formation of infinite chains of molecules, held together by weak intermolecular C—H⋯O hydrogen bonds. A theoretical investigation of the hydrogen bonding, based on density functional theory (DFT) employing periodic boundary conditions, is in agreement with the experimental data. The cluster approach shows that the influence of the crystal field and of hydrogen‐bond formation are responsible for the deformation of the 2‐oxazoline ring, which is not planar and adopts a 4T3 (C3TC2) conformation. 相似文献
3.
Dalma Gyepesov Vratislav Langer 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(2):111-113
The structure analysis of so‐called 9CaO·4CrO3·Cr2O3 proved it to be the title compound, decacalcium hexakis[chromate(V)] chromate(VI), with the simultaneous presence of unusual chromium oxidation states. The structure determination was carried out on a crystal that had inversion twinning. The CrVIO4 tetrahedron is situated on a threefold axis and is disordered over two possible orientations that share three O atoms, while the CrVO4 tetrahedra are in general positions and are ordered. The charge is balanced by Ca2+ cations, one of which is located on a threefold axis. The Ca2+ ions are coordinated by six, seven or eight O atoms. The compound is a significant phase in the CaO–CrOx system and its formation reduces the refractoriness of calcium‐rich compositions in an oxidizing atmosphere. 相似文献
4.
Vratislav Langer Dalma Gyepesov Mria Kohútov Aladr Valent 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(5):m208-m210
The title racemic complex, bis[μ‐N‐(2‐oxidobenzylidene)‐d ,l ‐glutamato(2−)]bis[(isoquinoline)copper(II)] ethanol disolvate, [Cu2(C12H11NO5)2(C9H7N)2]·2C2H6O, adopts a square‐pyramidal CuII coordination mode with a tridentate N‐salicylideneglutamato Schiff base dianion and an isoquinoline ligand bound in the basal plane. The apex of the pyramid is occupied by a phenolic O atom from the adjacent chelate molecule at an apical distance of 2.487 (3) Å, building a dimer located on the crystallographic inversion center. The Cu...Cu spacing within the dimers is 3.3264 (12) Å. The ethanol solvent molecules are hydrogen bonded to the dimeric complex molecules, forming infinite chains in the a direction. The biological activity of the title complex has been studied. 相似文献
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6.
Vratislav Langer Pavol Mach Dalma Gyepesov Lucia Andrezlov Mria Kohútov 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(11):m326-m328
In the structure of trans‐bis(ethanol‐κO)tetrakis(1H‐imidazole‐κN3)copper(II) bis[μ‐N‐(2‐oxidobenzylidene)‐D,L‐glutamato]‐κ4O1,N,O2′:O2′;κ4O2′:O1,N,O2′‐bis[(1H‐imidazole‐κN3)cuprate(II)], [Cu(C3H4N2)4(C2H6O)2][Cu2(C15H14N3O5)2], both ions are located on centres of inversion. The cation is mononuclear, showing a distorted octahedral coordination, while the anion is a binuclear centrosymmetric dimer with a square‐pyramidal copper(II) coordination. An extensive three‐dimensional hydrogen‐bonding network is formed between the ions. According to B3LYP/6–31G* calculations, the two equivalent components of the anion are in doublet states (spin density located mostly on CuII ions) and are coupled as a triplet, with only marginal preference over an open‐shell singlet. 相似文献
7.
Vratislav Langer Dalma Gyepesov Pavel Mach Eva Scholtzov Marta Saliov Andrej Boh
Boris Gpr 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(4):o199-o202
Crystals of the title racemic compound, C11H13NO2, consist of two types of molecules (conformers); one molecule has an exocyclic OH group in an equatorial position and the other has this group in an axial position. Consequently, the hydrogen‐bond schemes for the two molecules are different. The molecules with equatorial OH groups create infinite parallel chains (formed by the same enantiomer), connected by centrosymmetric dimers of molecules (of mixed enantiomers), both with axial OH groups. Possible interconversion of the conformers and the flexibility of the molecule were studied by means of different MP2 and density functional theory (DFT) methods. The optimization of the structure by the DFT method confirmed the types of the hydrogen bonds. 相似文献
8.
We investigate and compare the performance of four optical transport schemes for distributing Local Multipoint Distribution Service (LMDS) signals using an optical fiber backbone. 相似文献
9.
Sipos P Zeller D Kuzmann E Vértes A Homonnay Z Walczak M Canton SE 《Dalton transactions (Cambridge, England : 2003)》2008,(41):5603-5611
To establish the structure of ferric ions in strongly alkaline (pH > 13) environments, aqueous NaOH solutions supersaturated with respect to Fe(III) and the solid ferric-hydroxo complex salts precipitating from them have been characterized with a variety of experimental techniques. From UV measurements, in solutions of pH > 13, only one kind of Fe(III)-hydroxo complex species was found to be present. The micro crystals obtained from such solutions were proven to be a new, so far unidentified solid phase. M?ssbauer spectra of the quick-frozen solution and that of the complex salt indicated a highly symmetrical ferric environment in both systems From the EXAFS and XANES spectra, the environment of the ferric ion in these solutions (both native and quick-frozen) and in the complex salt was found to be different. In the complex salt, the bond lengths are consistent with an octahedral coordination around the ferric centres. In solution, the coordination geometry of Fe(III) is most probably tetrahedral. Our results demonstrate that in strongly alkaline aqueous solutions, ferric ions behave very similarly to other structurally related tervalent ions, like Al(III) or Ga(III). 相似文献
10.