scholarly journals A Computational Study of Metallacycles Formed by Pyrazolate Ligands and the Coinage Metals M = Cu(I), Ag(I) and Au(I): (pzM)n for n = 2, 3, 4, 5 and 6. Comparison with Structures Reported in the Cambridge Crystallographic Data Center (CCDC)

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5108
Author(s):  
José Elguero ◽  
Ibon Alkorta
Keyword(s):  
Data Center ◽  
Computational Study ◽  
Crystallographic Data ◽  
Cambridge Structural Database ◽  
X Ray ◽  
Cambridge Crystallographic Data Center ◽  
Coinage Metals ◽  
Structural Database

The structures reported in the Cambridge Structural Database (CSD) for neutral metallacycles formed by coinage metals in their valence (I) (cations) and pyrazolate anions were examined. Depending on the metal, dimers and trimers are the most common but some larger rings have also been reported, although some of the larger structures are not devoid of ambiguity. M06-2x calculations were carried out on simplified structures (without C-substituents on the pyrazolate rings) in order to facilitate a comparison with the reported X-ray structures (geometries and energies). The problems of stability of the different ring sizes were also analyzed.

Spacer conformation in biologically active molecules

2004 ◽  
Vol 76 (5) ◽  
pp. 959-964 ◽  
Author(s):  
J. Karolak-Wojciechowska ◽  
A. Fruzinski
Keyword(s):  
Statistical Data ◽  
Population Analysis ◽  
Cambridge Structural Database ◽  
Biologically Active ◽  
Aliphatic Chain ◽  
X Ray ◽  
Flexible Spacer ◽  
Conformational Preferences ◽  
Structural Database ◽  
The One

Based on our contemporary studies on the structures of biologically active molecules, we focus our attention on the aliphatic chain and its conformation. That flexible spacer definitely influenced the balanced position of all pharmacophoric points in molecules of biological ligands. The one atomic linker and two or three atomic spacers with one heteroatom X =O, S, CH2, NH have been taken into account. The conformational preferences clearly depend on the heteroatom X. In the discussion, we utilize our own X-ray data, computation chemistry methods, population analysis, and statistical data from the Cambridge Structural Database (CSD).

scholarly journals A citation analysis of the Cambridge Crystallographic Data Centre

2001 ◽  
Vol 34 (3) ◽  
pp. 375-380 ◽  
Author(s):  
Jane Redman ◽  
Peter Willett ◽  
Frank H. Allen ◽  
Robin Taylor
Keyword(s):  
Citation Analysis ◽  
Basic Research ◽  
Crystallographic Data ◽  
Cambridge Structural Database ◽  
Cambridge Crystallographic Data Centre ◽  
Research Papers ◽  
Highly Cited Papers ◽  
Data Centre ◽  
Structural Database ◽  
Highly Cited

Citation analysis has been widely used to quantify the influence of research articles on the development of science. This paper reports a citation analysis of ten highly cited papers associated with the Cambridge Crystallographic Data Centre (CCDC), covering the variation of citation with time, the journals in which citations occur, and the types of organization and the geographic regions that use the Cambridge Structural Database. The ten most highly cited papers, comprising four database descriptions (CSD), two geometrical tabulations (TAB) and four basic research papers (RES), received a total of 8494 citations over the period 1981–1998, with more than half of these citations occurring in the literature published from 1995 onwards. The high citation rates of the database descriptions (3573 of 8494) indicate the value of crystallographic data. However, the large number of citations of the geometrical tables (3172) and the research papers (1767) indicate that this value resides not just in the raw data held in the Cambridge Structural Database, but also in the structural knowledge that can be derived from it. In the most recent years covered by the analysis (1995–1998), these ten CCDC publications have received more than 1000 citations per annum (CSD 507, TAB 398 and RES 153 citations per annum) and the detailed analysis shows that these papers, and the data that they discuss, are used not only by crystallographers but also by researchers across the entire range of the chemical sciences.

scholarly journals SYNTHESIS AND STRUCTURE OF 3,5-DIAMINO-1,2,4-TRIAZOLIUM TETRACHLORO-GALLATE

2019 ◽  
Vol 62 (4) ◽  
pp. 121-127
Author(s):  
Tatyana V. Kudayarova ◽  
Elena A. Danilova ◽  
Yuliya A. Piteva ◽  
Kristina E. Mochalina ◽  
Maxim V. Dmitriev
Keyword(s):  
Complex Compound ◽  
Crystal Packing ◽  
Intermolecular Hydrogen Bond ◽  
Cambridge Structural Database ◽  
X Ray Diffraction ◽  
Centrosymmetric Dimer ◽  
X Ray ◽  
Preferential Localization ◽  
Structural Database ◽  
Almost All

This paper discusses the synthesis and structure of a complex compound based on 3,5-diamino-1H-1,2,4-triazole (guanazole) with gallium ions, formed by the interaction of anhydrous gallium (III) chloride and guanazole in dried methanol. After distilling off the solvent under vacuum, the resulting product was washed with hexane, acetone. The target compound was extracted with acetonitrile, and slow evaporation of the latter at room temperature for three days resulted in beige-colored crystals, which were characterized by IR spectroscopy, elemental analysis, mass-spectrometry and X-ray diffraction analysis. The complex composition of gallate, C2H6N5+∙[GaCl4], exists as two crystallographically independent cations and two anions. The complex compound crystallizes in the centrosymmetric space group of the monoclinic syngony. The tetrachlorogallate anion is a slightly distorted tetrahedron, which is typical of structures of this type. 1,2,4-triazolium cations are selectively protonated on the N4 and N4A atoms, however, the site of the preferential localization of the positive charge is the N2 and N2A atoms. In addition to the electrostatic interaction of oppositely charged ions, a developed system of hydrogen bonds plays an important role in the stabilization of the crystal packing: almost all hydrogen and chlorine atoms are involved in its formation. Each of the crystallographically independent cations forms a centrosymmetric dimer due to the intermolecular hydrogen bond N2 – H2···N3 and N2A – H2A···N3A.  A full set of X-ray data is deposited into the Cambridge Structural Database of Compounds - the Cambridge Structural Database (Contributor CCDC 1894815) and it can be gotten from the site www.ccdc.cam.ac.uk/data_request/cif.

scholarly journals Arrays with Local Centers of Symmetry in Space Groups Pca21 and Pna21

1998 ◽  
Vol 54 (6) ◽  
pp. 921-924 ◽  
Author(s):  
R. E. Marsh ◽  
V. Schomaker ◽  
F. H. Herbstein
Keyword(s):  
Crystallographic Data ◽  
Cambridge Structural Database ◽  
Cambridge Crystallographic Data Centre ◽  
Asymmetric Unit ◽  
Space Groups ◽  
Data Centre ◽  
Structural Database

Of the several hundred structures in the Cambridge Structural Database [version 4.6 (1992), Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge, England] having space groups Pca21 or Pna21 and more than one molecule in the asymmetric unit (Z > 4), approximately three-quarters contain local centers of symmetry. These local centers, which are not crystallographic centers, occur predominantly near x = 1\over8, y = 1\over4 in Pca21 or near x = 1\over8, y = 0 in Pna21; this also holds for the limited number of examples we have examined of pseudo-centrosymmetric molecules with Z = 4. Local centers at these points create unusual correlations between corresponding atoms in the two molecules.

Searching for stereoisomerism in crystallographic databases: algorithm, analysis and chiral curiosities

2017 ◽  
Vol 73 (3) ◽  
pp. 453-465 ◽  
Author(s):  
E. Grothe ◽  
H. Meekes ◽  
R. de Gelder
Keyword(s):  
Computer Program ◽  
Crystallographic Data ◽  
Cambridge Structural Database ◽  
Algorithm Analysis ◽  
Automated Identification ◽  
Crystallographic Databases ◽  
Multiple Structures ◽  
Ring Structures ◽  
Structural Database

The automated identification of chiral centres in molecular residues is a non-trivial task. Current tools that allow the user to analyze crystallographic data entries do not identify chiral centres in some of the more complex ring structures, or lack the possibility to determine and compare the chirality of multiple structures. This article presents an approach to identify asymmetric C atoms, which is based on the atomic walk count algorithm presented by Rücker & Rücker [(1993),J. Chem. Inf. Comput. Sci.33, 683–695]. The algorithm, which we implemented in a computer program namedChiChi, is able to compare isomeric residues based on the chiral centres that were identified. This allows for discrimination between enantiomers, diastereomers and constitutional isomers that are present in crystallographic databases.ChiChiwas used to process 254 354 organic entries from the Cambridge Structural Database (CSD). A thorough analysis of stereoisomerism in the CSD is presented accompanied by a collection of chiral curiosities that illustrate the strength and versatility of this approach.

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