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1.
Polymorphic transformations of CoMoO4 were studied by means of high temperature X-ray measurements within the temperature range 25–1200°C. On heating phase a obtained from low temperature modification b a new modification a′ was discovered. Phase a obtained by thermal decomposition of solvated α-CoMoO4 shows different behaviour. At 700–930°C depending on the conditions of preparation it transforms irreversibly into still another modification a″. On cooling, a mixture of phases a + a″ is obtained, the presence of a″ being responsible for the explosionwise transition into b, observed around the room temperature. 相似文献
2.
Within the presented LCAS MS (linear combination of atomic spinors–molecular spinors) SCF formalism both large and small components of the spinor radial parts have been expanded within the Gaussian basis set. The respective expressions for matrix elements as well as for one- and two-electron integrals are given. 相似文献
3.
Based on the all-valence ZDO SCF approximation a procedure for estimating the basis set superposition error (BSSE ) in semiempirical CNDO /INDO methods has been proposed. The results of the calculation show that the BSSE effect may improve the results obtained from the standard CNDO /INDO supermolecule calculation. The estimated BSSE effect enables one to explain some recently reported artificial structures for water and ethylene dimers. 相似文献
4.
Magdalena Kloskowska Jarosaw Chojnacki Wiesaw Wojnowski Barbara Becker 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(11):m541-m544
The title complex, [Li2(D2O)6][Li(C9H27SSiO3)2]2·2D2O, is the first compound with an S—M bond (M = alkali metal) within an unusual type of lithate anion, [Li(SR)2]− {where R is Si[OC(CH3)3]3}. There is a centre of symmetry located in the middle of the Li2O2 ring of the cation. All Li atoms are four‐coordinate, with LiO4 (cations) and LiO2S2 (anions) cores. The singly charged [Li(SR)2]− anions are well separated from the doubly charged [Li2(D2O)6]2+ cations; the distance between Li atoms from differently charged ions is greater than 5 Å. Both ion types are held within an extended network of O—D⋯O and O—D⋯S hydrogen bonds. 相似文献
5.
The synthesis of simple, chromogenic pyridine-2,6-dicarboxylic acid amides, derivatives of isomeric nitroanilines and aminonitrophenols, and their ion binding properties are described. The ligands' response to ionic species was examined by naked eye and was studied with the use of UV–vis spectroscopy in DMSO and its mixture with water. The effect of the localisation and the type of the substituents in aromatic rings were discussed. 1H NMR experiments were carried out to probe the mechanism of anion recognition, i.e. complexation via hydrogen bond formation versus ligand deprotonation. A selective response of N,N′-bis(2-hydroxy-4-nitrophenyl)pyridine-2,6-dicarboxamide (L5) towards dihydrogen phosphate was found in both DMSO and DMSO–water (95:5) solvent mixture. The structure of N,N′-bis(2-hydroxy-5-nitrophenyl)pyridine-2,6-dicarboxamide (L4) was confirmed by X-ray crystallography. 相似文献
6.
Andrzej Okuniewski Jaroslaw Chojnacki Katarzyna Baranowska Barbara Becker 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(2):195-198
Two new dialkylammonium thiosulfates, namely bis(diisopropylammonium) thiosulfate, 2C6H16N+·S2O32−, (I), and bis(tert‐butylammonium) thiosulfate, 2C4H12N+·S2O32−, (II), have been characterized. The secondary ammonium salt (I) crystallizes with Z = 4, while the primary ammonium salt (II), with more hydrogen‐bond donors, crystallizes with Z = 8 and a noncrystallographic centre of inversion. In both salts, the organic cations and thiosulfate anions are linked within extensive N—H...O and N—H...S hydrogen‐bond networks, forming extended two‐dimensional layers. Layers are parallel to (10) in (I) and to (002) in (II), and have a polar interior and a nonpolar hydrocarbon exterior. The layered structure and hydrogen‐bond motifs observed in (I) and (II) are similar to those in related ammonium sulfates. 相似文献
7.
Ewa Wagner-Wysiecka Paulina Szulc Elbieta Luboch Jarosaw Chojnacki Pawe Sowiski Katarzyna Szwarc-Karabyka 《Molecules (Basel, Switzerland)》2022,27(6)
The preparation and characterization of products of the photochemical and thermochemical rearrangements of 19-membered azoxybenzocrowns with two, bulky, tert-butyl substituents in benzene rings in the para positions to oligooxyethylene fragments (meta positions to azoxy group, i.e., t-Bu-19-Azo-O have been presented. In photochemical rearrangement, two colored typical products were expected, i.e., 19-membered o-hydroxy-m,m′-di-tert-butyl-azobenzocrown (t-Bu-19-o-OH) and 19-membered p-hydroxy-m,m′-di-tert-butyl-azobenzocrown (t-Bu-19-p-OH). In experiments, two colored atypical macrocyclic derivatives, one 6-membered and one 5-membered ring, bearing an aldehyde group (t-Bu-19-al) or intramolecular ester group (t-Bu-20-ester), were obtained. Photochemical rearrangement led to one more macrocyclic product being isolated and identified: a 17-membered colorless compound, without an azo moiety, t-Bu-17-p-OH. The yield of the individual compounds was significantly influenced by the reaction conditions. Thermochemical rearrangement led to t-Bu-20-ester as the main product. The structures of the four crystalline products of the rearrangement—t-Bu-19-o-OH, t-Bu-19-p-OH, t-Bu-20-ester and t-Bu-17-p-OH—were determined by the X-ray method. Structures in solution of atypical derivatives (t-Bu-19-al and t-Bu-20-ester) and t-Bu-19-p-OH were defined using NMR spectroscopy. For the newly obtained hydroxyazobenzocrowns, the azo–phenol⇄quinone–hydrazone tautomeric equilibrium was investigated using spectroscopic methods. Complexation studies of alkali and alkaline earth metal cations were studied using UV-Vis absorption spectroscopy. 1H NMR spectroscopy was additionally used to study the cation recognition of metal cations. Cation binding studies in acetonitrile have shown high selectivity towards calcium over magnesium for t-Bu-19-o-OH. 相似文献
8.
The interaction of atomic antihydrogen with helium has been studied within the Born-Oppenheimer approximation. The linear combination of explicitly correlated Gaussian functions was used as the ansatz for the wave function of light particles. The potential energy curve with the minimum at 3.63 bohr and the barrier at 2.42 bohr has been obtained. 相似文献
9.
The perturbation energies for model ammonia and imidazole systems have been calculated using all valence molecular orbitais in a LCMO formulation. With semi-empirical parametrization the method was extended to the adenine-thymine and guanine-cytosine base pairs. The results indicate that the σ-σ interactions are dominant, whereas the π-π component confers only a negligible contribution to the stabilization energy. 相似文献
10.
Anna Śmiechowska Witold Przychodzeń Jarosław Chojnacki Piotr Bruździak Jacek Namieśnik Agnieszka Bartoszek 《Structural chemistry》2010,21(5):955-964
Adducts of natural allyl, phenethyl, and benzyl isothiocyanates and 2-amino-1-methylbenzimidazole were synthesized. After
optimization of the reaction conditions, the target 2-benzimidazolylthioureas were obtained in reasonable yields. The detailed
molecular and crystal structures of these compounds were characterized by spectroscopic and X-ray methods. Spectral analysis
demonstrated that N-(1-methylbenzimidazolyl)-N′-allylthiourea, N-(1-methylbenzimidazolyl)-N′-benzylthiourea, and N-(1-methylbenzimidazolyl)-N′-phenethylthiourea exist in solution in an unprecedented three tautomeric forms, whose structures were corroborated unambiguously. 相似文献