Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry最新文献_第5页

A revised interpretation of the structure of (NH4)2Ge7O15 in the light of the Extended Zintl–Klemm Concept 根据扩展Zintl-Klemm概念对(NH4)2Ge7O15结构的修正解释

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S2052520616019181

A. Vegas, H. Jenkins

{"title":"A revised interpretation of the structure of (NH4)2Ge7O15 in the light of the Extended Zintl–Klemm Concept","authors":"A. Vegas, H. Jenkins","doi":"10.1107/S2052520616019181","DOIUrl":"https://doi.org/10.1107/S2052520616019181","url":null,"abstract":"The structure of (NH4)2Ge7O15 recently described as being a microporous material containing rings, in which GeO6 octahedra coexist with GeO4 tetrahedra, is re-examined in the light of the Extended Zintl–Klemm Concept as applied to cations in oxides. The Ge[6] atoms together with the NH4+ groups act as true cations, transferring their 6 valence electrons to the acceptor Ge2O5 moiety, so converting it into the [Ge6O15]6−≡3(Ψ-As2O5) ion (where Ψ refers to a pseudo-lattice) and yielding threefold connectivity. The tetrahedral Ge network shows similarities with the Sb2O3 analogue. At the same time, the Ge[6] atoms are connected to other Ge[4] atoms forming blocks that are part of a rutile-type GeO2 structure. Such an analysis shows that both substructures (the Zintl polyanion and the rutile fragments) must be satisfied simultaneously as has already been illustrated in previous articles which considered stuffed-bixbyites [Vegas et al. (2009). Acta Cryst. B65, 11–21] as well as the compound FeLiPO4 [Vegas (2011). Struct. Bond. 138, 67–91]. This new insight conforms well to previous (differential thermal analysis) DTA–TGA (thermogravimetric analysis) experiments [Cascales et al. (1998). Angew. Chem. Int. Ed. 37, 129–131], which show endothermic loss of NH3 and H2O to give rise to the metastable structure Ge7O14, which further collapses to the rutile-type GeO2 structure. We analyze the stability change in terms of ionic strength, I, and so provide a means of rationalizing the driving force behind this concept capable of explaining the atomic arrangements found in these types of crystal structures. Although the concept was formulated in 2003, later than the publication of the germanate structure, it was not used or else ignored by colleagues who solved this crystal structure.","PeriodicalId":6887,"journal":{"name":"Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry","volume":"1 1","pages":"94-100"},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84063843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

A priori checking of the light-response and data quality before extended data collection in pump–probe photocrystallography experiments 泵浦探针光晶体学实验中扩展数据采集前的光响应和数据质量的先验检查

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S2052520616017558

P. Coppens, A. Makal, Bertrand Fournier, K. Jarzembska, R. Kamiński, K. Basuroy, E. Trzop

引用次数: 6

Crystal structure prediction by ionic network analysis: the example of (p–T–X)-structure relationships in olivines 用离子网络分析预测晶体结构:橄榄石中(p-T-X)-结构关系的例子

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S2052520616018308

N. Thomas

{"title":"Crystal structure prediction by ionic network analysis: the example of (p–T–X)-structure relationships in olivines","authors":"N. Thomas","doi":"10.1107/S2052520616018308","DOIUrl":"https://doi.org/10.1107/S2052520616018308","url":null,"abstract":"The method of Ionic Network Analysis (INA) is defined by reference to the known crystal structures of olivine minerals. It is based on a reversible transformation between two alternative representations of ionic crystal structures: (a) the crystallographic and (b) the interactional. Whereas the former encompasses unit-cell parameters and atomic coordinates, the latter consists of selected interaction vectors between ions. Since the lengths and orientations of these vary only slightly between crystal structures obtained under systematically varying (p, T, X) conditions, they may be used to predict the crystal structures at intermediate (p, T, X) values by interpolation. Two interactional networks are constructed, one for the anions and the other for cations. As both networks lead to independent calculated values of the unit-cell parameters, it is possible to exploit the known, continuous (p, T, X) variations of cell parameters as normative constraints for the prediction of atomic coordinates within a predictive structural refinement procedure. Continuously varying structurally based parameters such as the volumes of cation coordination polyhedra may likewise be used. The choice of olivines for developing the method has been guided by the availability of pressure, temperature and compositional structural data for them. However, the ideas are expounded sufficiently generally for the method to be applied to other minerals.","PeriodicalId":6887,"journal":{"name":"Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry","volume":"77 1","pages":"74-86"},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84654112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Charge density analysis of metformin chloride, a biguanide anti-hyperglycemic agent 双胍类抗高血糖药物二甲双胍氯的电荷密度分析

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S2052520616017844

R. N. Devi, C. Jelsch, S. Israel, E. Aubert, C. Anzline, Amar A. Hosamani

{"title":"Charge density analysis of metformin chloride, a biguanide anti-hyperglycemic agent","authors":"R. N. Devi, C. Jelsch, S. Israel, E. Aubert, C. Anzline, Amar A. Hosamani","doi":"10.1107/S2052520616017844","DOIUrl":"https://doi.org/10.1107/S2052520616017844","url":null,"abstract":"The experimental charge density analysis of the anti-hyperglycemic agent metformin chloride with high-resolution X-ray diffraction data at low temperature (100 K) has been performed and these experimental results were compared with that derived from the corresponding periodic theoretical calculations at the B3LYP/6-31G** level of theory. The experimental and theoretical multipolar charge-density analyses of metformin chloride have been accomplished in order to understand its structural and electronic properties. The C and N atoms of the molecular backbone adopt a near trigonal geometry due to the occurrence of extensive delocalization/resonance of C—N bonds, as confirmed by topological analysis and also found by Natural Resonance Theory calculations performed in the isolated metformin cation. The molecule contains six C—N bonds and the topological bond order analysis shows that four bonds have bond orders close to 4/3 and two bonds can be considered as single. The analysis of numerical parameters of the valence shell charge concentration reports that the N3 atom, which forms two bonds with C atoms, possesses one non-bonding valence-shell charge concentration (VSCC) in the direction of the electron lone pair. Among the intermolecular interactions of the chloride atom with the H—C and H—N atoms, eight have been found to be shorter than the sum of van der Waals radii. The analysis of contacts on the Hirshfeld surface reveals that the H—N⋯Cl hydrogen bonds are enriched (over-represented) and act as the driving force in the crystal packing formation. The metformin cations form favorable electrostatic interactions with the chloride anions which have globally a stronger energy than the unfavorable cation/cation interactions.","PeriodicalId":6887,"journal":{"name":"Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry","volume":"29 1","pages":"10-22"},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89613026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 15

Neutron and X-ray investigations of the Jahn–Teller switch in partially deuterated ammonium copper Tutton salt, (NH4)2[Cu(H2O)6](SO4)2 部分氘化铜盐(NH4)2[Cu(H2O)6](SO4)2中Jahn-Teller开关的中子和x射线研究

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S2052520616018412

M. R. Jørgensen, P. Piccoli, V. R. Hathwar, Xiaoping Wang, C. Hoffmann, A. Yakovenko, G. J. Halder, J. Schlueter, B. Iversen, A. Schultz

引用次数: 1

Formation of co-racemic uranyl chromate constructed from chiral layers of different topology 由不同拓扑结构的手性层构建共消旋铀酰铬酸盐的形成

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S205252061601917X

O. Siidra, E. Nazarchuk, S. Bocharov, W. Depmeier, A. Zadoya

{"title":"Formation of co-racemic uranyl chromate constructed from chiral layers of different topology","authors":"O. Siidra, E. Nazarchuk, S. Bocharov, W. Depmeier, A. Zadoya","doi":"10.1107/S205252061601917X","DOIUrl":"https://doi.org/10.1107/S205252061601917X","url":null,"abstract":"Four new inorganic uranyl chromates were obtained by evaporation and hydrothermal methods: [(CH3)2NH2]2[(UO2)2(CrO4)3(H2O)](H2O) (1), K(Rb0.6K0.4)[(UO2)2(CrO4)3(H2O)](H2O)3 (2) [(CH3)3CNH3]2[(UO2)2(CrO4)3H2O] (3), [(CH3)2NH2]4[(UO2)2(CrO4)3H2O]2(H2O) (4). Their structures are based on two-dimensional chiral or achiral units with the composition [(UO2)2(CrO4)3(H2O)]2− and two types of topologies (A or/and B). The structural architecture of (4) is unique amongst all known uranyl-based structures, and unusual among hybrid organic/inorganic structures in general as it contains layers of identical composition, but of different topology. The unique structural configurations and non-centrosymmetry in (1) and (4) is governed by selective formation of hydrogen bonding rather than by the formation of hydrophobic and hydrophilic zones in the organic interlayer. It is shown that chiral architectures in uranyl systems may form from achiral building units as observed in (3) and (4). This is somewhat analogous to certain organic compounds, where achiral molecules are also able to form chiral layers. Within the concept of such an interpretation the structure of (3) can then be described as a racemate consisting of two A and A′ chiral layers. In a similar approach the structure of (4) can be interpreted as being formed by four chiral layers. Layer pairs AA′ and BB′ can then be considered as racemic pairs and the whole structure is a co-racemate built by a combination of two racemates. Two-stage formation can be suggested for (4).","PeriodicalId":6887,"journal":{"name":"Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry","volume":"26 1","pages":"101-111"},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89928664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Deformations of the α-Fe2O3 rhombohedral lattice across the Néel temperature α-Fe2O3菱形晶格在nsamel温度下的变形

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S2052520616017935

Piotr Fabrykiewicz, M. Stekiel, I. Sosnowska, R. Przeniosło

引用次数: 5

Synchrotron X-ray diffuse scattering from a stable polymorphic material: terephthalic acid, C8H6O4 稳定多晶材料:对苯二甲酸C8H6O4的同步加速器x射线漫射

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S2052520616018801

D. Goossens, E. Chan

{"title":"Synchrotron X-ray diffuse scattering from a stable polymorphic material: terephthalic acid, C8H6O4","authors":"D. Goossens, E. Chan","doi":"10.1107/S2052520616018801","DOIUrl":"https://doi.org/10.1107/S2052520616018801","url":null,"abstract":"Terephthalic acid (TPA, C8H6O4) is an industrially important chemical, one that shows polymorphism and disorder. Three polymorphs are known, two triclinic [(I) and (II)] and one monoclinic (III). Of the two triclinic polymorphs, (II) has been shown to be more stable in ambient conditions. This paper presents models of the local order of polymorphs (I) and (II), and compares the single-crystal diffuse scattering (SCDS) computed from the models with that observed from real crystals. TPA shows relatively weak and less-structured diffuse scattering than some other polymorphic materials, but it does appear that the SCDS is less well modelled by a purely harmonic model in polymorph (I) than in polymorph (II), according to the idea that the diffuse scattering is sensitive to anharmonicity that presages a structural phase transition. The work here verifies that displacive correlations are strong along the molecular chains and weak laterally, and that it is not necessary to allow the —COOH groups to librate to successfully model the diffuse scattering – keeping in mind that the data are from X-ray diffraction and not directly sensitive to H atoms.","PeriodicalId":6887,"journal":{"name":"Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry","volume":"106 1","pages":"112-121"},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74879517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Structures and thermal stability of the α-LiNH4SO4 polytypes doped with Er3+ and Yb3+ Er3+和Yb3+掺杂α-LiNH4SO4多型材料的结构和热稳定性

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S2052520616019028

N. Sabalisck, C. Guzmán-Afonso, C. González-Silgo, M. Torres, J. Pasán, J. del-Castillo, D. Ramos-Hernández, A. Hernández-Suárez, L. Mestres

{"title":"Structures and thermal stability of the α-LiNH4SO4 polytypes doped with Er3+ and Yb3+","authors":"N. Sabalisck, C. Guzmán-Afonso, C. González-Silgo, M. Torres, J. Pasán, J. del-Castillo, D. Ramos-Hernández, A. Hernández-Suárez, L. Mestres","doi":"10.1107/S2052520616019028","DOIUrl":"https://doi.org/10.1107/S2052520616019028","url":null,"abstract":"In order to clarify the polymorphism in the lithium sulfate family, LiREx(NH4)1 − xSO4 (0.5 ≤ x ≤ 4.0 mol%, nominal value; RE = Er3+, Yb3+ and Dy3+) crystals were grown from aqueous solution by slow evaporation between 298 and 313 K. The doping of the samples allowed us to obtain two polymorphic forms, α and β, of LiNH4SO4 (LAS). By means of X-ray diffraction (XRD) in single crystals, we determined the crystal structures of two new α-polytypes, which we have named α1- and α2-LAS. They present the same space group P21/c and the following relation among their lattice parameters: a2 = −c1, b2 = −b1, c2 = −2a1 − c1. In order to evaluate the stability of the new α-polytypes, we performed thermal analysis, X-ray diffraction and dielectric spectroscopy on single crystals and polycrystalline samples over the cyclic temperature range: 190 → 575 → 190 K. The results obtained by all the techniques used in this study demonstrate that α-polytypes are stable across a wide range of temperatures and they show an irreversible phase transition to the paraelectric β-phase above 500 K. In addition, a comparative study of α- and β-polytypes shows that both polymorphic structures have a common axis, with a possible intergrowth that facilitates their coexistence and promotes the reconstructive α → β transition. This intergrowth was related to small anomalies detected between 240 and 260 K, in crystals with an α-habit.","PeriodicalId":6887,"journal":{"name":"Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry","volume":"21 1","pages":"122-133"},"PeriodicalIF":0.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90750031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Crystallographic features of ammonium fluoroelpasolites: dynamic orientational disorder in crystals of (NH4)3HfF7 and (NH4)3Ti(O2)F5 铵氟铝溶石的晶体学特征:(NH4)3HfF7和(NH4)3Ti(O2)F5晶体的动态取向紊乱

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry Pub Date : 2017-02-01 DOI: 10.1107/S2052520616017534

A. Udovenko, Alexander A. Karabtsovb, Natalia M. Laptasha

引用次数: 8