Crystal chemistry of tetraradial species. Part 2. Crystal structures of Et4NI, Ph4PBr•H2O, and Ph4PBr•2H2O

Beverly R. Vincent; Osvald Knop; Anthony Linden; T. Stanley Cameron; Katherine N. Robertson

doi:10.1139/v88-474

Crystal chemistry of tetraradial species. Part 2. Crystal structures of Et4NI, Ph4PBr•H2O, and Ph4PBr•2H2O

Canadian Journal of Chemistry ◽

10.1139/v88-474 ◽

1988 ◽

Vol 66 (12) ◽

pp. 3060-3069 ◽

Cited By ~ 21

Author(s):

Beverly R. Vincent ◽

Osvald Knop ◽

Anthony Linden ◽

T. Stanley Cameron ◽

Katherine N. Robertson

Keyword(s):

Crystal Structure ◽

Crystal Structures ◽

Crystal Chemistry ◽

Cyclic Dimer ◽

Nias Type ◽

First Time

The crystal structure of Et4NI [Formula: see text], a = 8.860(2) Å, c = 6.933(1) Å, Z = 2) has been redetermined and those of Ph4PBr•H2O ([Formula: see text], a = 10.005(3) Å, b = 10.659(2) Å, c = 10.697(4) Å, α = 102.61(2)°, β = 83.39(3)°, γ = 108.09(3)°, Z = 2) and Ph4PBr•2H2O (Pnma, a = 16.255(4) Å, b = 10.810(4) Å, c = 12.667(9) Å, Z = 4) have been determined for the first time. In the Et4NI structure Et4N+ cations in an extended S4 conformation and I− anions are arranged in a zincblende-type packing. The two hydrate structures are ionic and very similar. The anion in the monohydrate is a centrosymmetric cyclic dimer [Br2(OH2)2]2−; in the dihydrate the anion, which is an almost planar infinite [Br−(OH2)4/2]x chain 11b, appears to be of a novel type. If the H2O molecules are not considered, the ion packing in both hydrates may be regarded as of the anti-NiAs type. The ion packing in R4EX structures and the conformation of the Et4N+ ion in crystals are discussed in some detail.

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New insight into the crystal structure of orthorhombic edingtonite: evidence for a split Ba site

Mineralogical Magazine ◽

10.1180/0026461046810178 ◽

2004 ◽

Vol 68 (1) ◽

pp. 167-175 ◽

Cited By ~ 8

Author(s):

G. D. Gatta ◽

T. Boffa Ballaran

Keyword(s):

Crystal Structure ◽

British Columbia ◽

Crystal Structures ◽

Lattice Parameters ◽

Space Group ◽

Physicochemical Conditions ◽

Report Data ◽

First Time ◽

Insight Into

AbstractOrthorhombic edingtonite has been found coexisting with tetragonal edingtonite in a specimen from Ice River, British Columbia, Canada.We report data on the composition and crystal structure of the orthorhombic sample. Lattice parameters are: a = 9.5341(6), b = 9.6446(6), c = 6.5108(7)Å, V = 598.68(8)Å 3. The crystal structure was refined in space group P 21212 to R1 = 1.8% using 879 observed reflections. For the first time, evidence for splitting of the extra-framework Ba site in two different sites (Ba1, Ba2), ~0.37 Å apart, is demonstrated. A comparison with the published crystal structures of tetragonal and orthorhombic edingtonite is made.The present result supports the suggestion that the two edingtonite phases are a consequence of different nucleation phenomena and not different physicochemical conditions.

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Crystal chemistry of zirconosilicates and their analogs: topological classification of MT frameworks and suprapolyhedral invariants

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768101021619 ◽

2002 ◽

Vol 58 (2) ◽

pp. 198-218 ◽

Cited By ~ 61

Author(s):

G. D. Ilyushin ◽

V. A. Blatov

Keyword(s):

Crystal Structure ◽

Crystal Structures ◽

Crystal Chemistry ◽

Three Dimensional ◽

Geometrical Interpretation ◽

Topological Classification ◽

Hierarchical Analysis ◽

Framework Structure ◽

Coordination Spheres

The first attempt is undertaken to consider systematically topological structures of zirconosilicates and their analogs (60 minerals and 34 synthetic phases), where the simplest structure units are MO6 octahedra and TO4 tetrahedra united by vertices ([TO4]:[MO6] = 1:1–6:1). A method of analysis and classification of mixed three-dimensional MT frameworks by topological types with coordination sequences {N k } is developed, which is based on the representation of crystal structure as a finite `reduced' graph. The method is optimized for the frameworks of any composition and complexity and implemented within the TOPOS3.2 program package. A procedure of hierarchical analysis of MT-framework structure organization is proposed, which is based on the concept of polyhedral microensemble (PME) being a geometrical interpretation of coordination sequences of M and T nodes. All 12 theoretically possible PMEs of MT 6 polyhedral composition are considered where T is a separate and/or connected tetrahedron. Using this methodology the MT frameworks in crystal structures of zirconosilicates and their analogs were analyzed within the first 12 coordination spheres of M and T nodes and related to 41 topological types. The structural correlations were revealed between rosenbuschite, lavenite, hiortdahlite, woehlerite, siedozerite and the minerals of the eudialyte family.

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Crystal chemistry of orthosilicates and their analogs: the classification by topological types of suprapolyhedral structural units

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768102015070 ◽

2002 ◽

Vol 58 (6) ◽

pp. 948-964 ◽

Cited By ~ 23

Author(s):

G. D. Ilyushin ◽

V. A. Blatov ◽

Yu. A. Zakutkin

Keyword(s):

Crystal Structure ◽

Phase Transitions ◽

Crystal Structures ◽

Crystal Chemistry ◽

Topological Classification ◽

Structural Units ◽

Coordination Sequence ◽

Coordination Spheres

A method is developed for the analysis and classification of orthosilicates and their analogs Mx (TO4) y containing M cations and tetrahedral TO4 anions. The method uses the concepts of coordination sequence and crystal structure `reduced' graphs and is optimized for orthostructures of any complexity. First, the suprapolyhedral level of crystal structure organization was studied, where T tetrahedra were considered as templates for condensing M polyhedra, constructing as a result T polyhedral microensembles. Using this methodology, the crystal structures of 54 orthosilicates and orthogermanates were analyzed within the first 12 coordination spheres of T nodes and were arranged into 21 topological types. The topological types were expanded with the analogs found within the orthostructures of phosphates, sulfates etc. T polyhedral microensembles were used for the topological classification of reconstruction mechanisms of thermal and baric phase transitions of orthosilicates.

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Crystal structures of a β-trefoil lectin from Entamoeba histolytica in monomeric and a novel disulfide bond-mediated dimeric forms

Glycobiology ◽

10.1093/glycob/cwaa001 ◽

2020 ◽

Vol 30 (7) ◽

pp. 474-488 ◽

Cited By ~ 1

Author(s):

Farha Khan ◽

Devanshu Kurre ◽

K Suguna

Keyword(s):

Crystal Structure ◽

Crystal Structures ◽

Entamoeba Histolytica ◽

Disulfide Bond ◽

Structural Basis ◽

Free Form ◽

Biophysical Characterization ◽

Biophysical Studies ◽

First Time

Abstract β-Trefoil lectins are galactose/N-acetyl galactosamine specific lectins, which are widely distributed across all kingdoms of life and are known to perform several important functions. However, there is no report available on the characterization of these lectins from protozoans. We have performed structural and biophysical studies on a β-trefoil lectin from Entamoeba histolytica (EntTref), which exists as a mixture of monomers and dimers in solution. Further, we have determined the affinities of EntTref for rhamnose, galactose and different galactose-linked sugars. We obtained the crystal structure of EntTref in a sugar-free form (EntTref_apo) and a rhamnose-bound form (EntTref_rham). A novel Cys residue-mediated dimerization was revealed in the crystal structure of EntTref_apo while the structure of EntTref_rham provided the structural basis for the recognition of rhamnose by a β-trefoil lectin for the first time. To the best of our knowledge, this is the only report of the structural, functional and biophysical characterization of a β-trefoil lectin from a protozoan source and the first report of Cys-mediated dimerization in this class of lectins.

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Crystal chemistry of tetraradial species. Part 4. Hydrogen bonding to aromatic π systems: crystal structures of fifteen tetraphenylborates with organic ammonium cations

Canadian Journal of Chemistry ◽

10.1139/v94-161 ◽

1994 ◽

Vol 72 (5) ◽

pp. 1273-1293 ◽

Cited By ~ 45

Author(s):

Pradip K. Bakshi ◽

Antony Linden ◽

Beverly R. Vincent ◽

Stephen P. Roe ◽

D. Adhikesavalu ◽

...

Keyword(s):

Crystal Structure ◽

Hydrogen Bonding ◽

Crystal Structures ◽

Crystal Chemistry ◽

Phenyl Ring ◽

Orientational Disorder ◽

Compromise Solutions ◽

The Mean ◽

General Organization

The aim of this investigation is to provide a classification and examples of N—H …π (and also O—H …π) bonds to the aromatic π systems in organic ammonium tetraphenylborates that would serve as reference for X—H …π(arene) bonds in general. To this end the crystal structures of the tetraphenylborates of the following cations have been determined: Me3NH+, Et3NH+, quinuclidinium, DabcoH+, Et(iso-Pr)2NH+ (monohydrate), (Ph3B)NH[—(CH2)2—]2NHMe+ (Me2CO solvate), Me2NH2+ (MeCN and Et2CO solvates), Et2NH2+, (iso-Pr)2NH2+, azoniacycloheptane, guanidinium (monohydrate), MeNH3+, EtNH3+, and 1-adamantammonium (monohydrate). These structures contain a variety of normal, bifurcated, and trifurcated N—H …π bonds as well as normal O—H …π bonds to the phenyl groups of the anion. The X—H …π bonds will form whenever opportunity arises, even though the result may be unfavourable bonding geometry. Branched bonds and orientational disorder represent compromise solutions in situations where the H(X) hydrogens are presented with competing phenyl acceptors or where the general organization of the crystal structure offers unfavourable bonding conditions to these hydrogens. The distributions of the distances from X or H(X) to the centre of the phenyl-ring skeleton are analyzed in detail, as are also those of the mean X … C and H(X)… C distances to the ring carbons.

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Syntheses, spectroscopy, and crystal structures of 3-(4-bromophenyl)-1,5-diphenylformazan and the 3-(4-bromophenyl)-1,5-diphenylverdazyl radical and the crystal structure of the by-product 5-anilino-3-(4-bromophenyl)-1-phenyl-1H-1,2,4-triazole

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989018001913 ◽

2018 ◽

Vol 74 (3) ◽

pp. 292-297 ◽

Cited By ~ 4

Author(s):

Gregor Schnakenburg ◽

Andreas Meyer

Keyword(s):

Crystal Structure ◽

Crystal Structures ◽

Organic Compounds ◽

Spectroscopic Data ◽

Structural Data ◽

The Other ◽

Side Product ◽

Axis Direction ◽

Verdazyl Radical ◽

First Time

The title compounds, C19H15BrN4, C20H16BrN4and C20H15BrN4, are nitrogen-rich organic compounds that are related by their synthesis. The verdazyl radical, in which stacking leads to antiferromagnetic interactions, was reported previously [Iwaseet al.(2013).Phys. Rev. B,88, 184431]. For this compound, improved structural data and spectroscopic data are presented. The other two compounds have been crystallized for the first time and form stacks of dimers, roughly along thea-axis direction of the crystal. The formazan molecule shows signs of rapid intramolecular H-atom exchange typical for this class of compounds and spectroscopic data are provided in addition to the crystal structure. The triazole compound appears to be a side-product of the verdazyl synthesis.

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The Crystal Structure of WC Type ZrTe. Advantages in Chemical Bonding as Contrasted to NiAs Type ZrTe

Zeitschrift für Naturforschung B ◽

10.1515/znb-1999-0906 ◽

1999 ◽

Vol 54 (9) ◽

pp. 1125-1128 ◽

Cited By ~ 9

Author(s):

Gissur Örlygsson ◽

Bernd Harbrecht

Keyword(s):

Crystal Structure ◽

Local Minimum ◽

Structure Type ◽

Metal Deficiency ◽

Nias Type Structure ◽

The Stability ◽

Nias Type ◽

First Time ◽

Extended Hückel Calculations

Single crystals of WC type ZrTe were prepared from the elements. A single crystal structure determination of this structure type was performed for the first time: ZrTe (WC) crystallizes in the hexagonal space group P6̄m2 (No. 187), hP2, Z - 1, a - 377.06(5), c = 386.05(8) pm; 84 reflections, 5 variables, R(F) = 0.037. The distinctions in bonding for ZrTe (WC) and a hypothetical stoichiometric ZrTe crystallizing in the NiAs type structure were analyzed on the basis of extended Hückel calculations. Heteronuclear interactions contribute most strongly to the stability of both structures. Attractive Zr-Zr interactions energetically favour ZrTe (WC) relative to ZrTe (NiAs). The Fermi level of ZrTe (WC) resides in a local minimum of the DOS, whereas that of ZrTe (NiAs) intersects a local DOS maximum, and is pushed up by about 0.5 eV, expressing the decisive destabilization of NiAs type ZrTe. As a consequence, metal deficiency is observed for ZrTe (NiAs), in contrast to ZrTe (WC).

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Crystal Chemistry and Structural Complexity of Natural and Synthetic Uranyl Selenites

Crystals ◽

10.3390/cryst9120639 ◽

2019 ◽

Vol 9 (12) ◽

pp. 639 ◽

Cited By ~ 4

Author(s):

Vladislav V. Gurzhiy ◽

Ivan V. Kuporev ◽

Vadim M. Kovrugin ◽

Mikhail N. Murashko ◽

Anatoly V. Kasatkin ◽

...

Keyword(s):

Crystal Structure ◽

Crystal Structures ◽

Crystal Chemistry ◽

Topological Analysis ◽

Radioactive Decay ◽

Structural Complexity ◽

Building Blocks ◽

Synthetic Compounds ◽

Structural Architecture ◽

Natural And Synthetic

Comparison of the natural and synthetic phases allows an overview to be made and even an understanding of the crystal growth processes and mechanisms of the particular crystal structure formation. Thus, in this work, we review the crystal chemistry of the family of uranyl selenite compounds, paying special attention to the pathways of synthesis and topological analysis of the known crystal structures. Comparison of the isotypic natural and synthetic uranyl-bearing compounds suggests that uranyl selenite mineral formation requires heating, which most likely can be attributed to the radioactive decay. Structural complexity studies revealed that the majority of synthetic compounds have the topological symmetry of uranyl selenite building blocks equal to the structural symmetry, which means that the highest symmetry of uranyl complexes is preserved regardless of the interstitial filling of the structures. Whereas the real symmetry of U-Se complexes in the structures of minerals is lower than their topological symmetry, which means that interstitial cations and H2O molecules significantly affect the structural architecture of natural compounds. At the same time, structural complexity parameters for the whole structure are usually higher for the minerals than those for the synthetic compounds of a similar or close organization, which probably indicates the preferred existence of such natural-born architectures. In addition, the reexamination of the crystal structures of two uranyl selenite minerals guilleminite and demesmaekerite is reported. As a result of the single crystal X-ray diffraction analysis of demesmaekerite, Pb2Cu5[(UO2)2(SeO3)6(OH)6](H2O)2, the H atoms positions belonging to the interstitial H2O molecules were assigned. The refinement of the guilleminite crystal structure allowed the determination of an additional site arranged within the void of the interlayer space and occupied by an H2O molecule, which suggests the formula of guilleminite to be written as Ba[(UO2)3(SeO3)2O2](H2O)4 instead of Ba[(UO2)3(SeO3)2O2](H2O)3.

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