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

2002 ◽  
Vol 58 (2) ◽  
pp. 198-218 ◽  
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.

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

2002 ◽  
Vol 58 (6) ◽  
pp. 948-964 ◽  
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.

The crystal structure of kalsilite, KAlSiO4

1965 ◽  
Vol 35 (272) ◽  
pp. 588-595 ◽  
Author(s):  
A. J. Perrotta ◽  
J. V. Smith
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Crystal Structures ◽  
Bond Angle ◽  
Three Dimensional ◽  
Full Matrix ◽  
Ideal Position ◽  
Wide Range ◽  
The Ideal

SummaryA full-matrix, three-dimensional refinement of kalsilite, KAlSi04 (hexagonal, a 5·16, c 8.69 Å, P6a), shows that the silicon and aluminium atoms are ordered. The respective tetrahedral distances of 1·61 and 1·74 Å agree with values of 1·61 and 1·75 Å taken to be typical of framework structures. As in nepheline, an oxygen atom is statistically distributed over three sites displaced 0·25 Å from the ideal position on a triad axis. This decreases the bond angle from 180° to 163° in conformity with observations on some other crystal structures. The potassiumoxygen distances of 2·77, 2·93, and 2·99 Å are consistent with the wide range normally found for this weakly bonded atom.

scholarly journals Crystal structure of 1-methoxy-2,2,2-tris(pyrazol-1-yl)ethane

2014 ◽  
Vol 70 (9) ◽  
pp. o1047-o1048 ◽  
Author(s):  
Ganna Lyubartseva ◽  
Sean Parkin ◽  
Morgan D. Coleman ◽  
Uma Prasad Mallik
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Three Dimensional ◽  
Dihedral Angles ◽  
Framework Structure ◽  
Compound C

The title compound, C12H14N6O, consists of three pyrazole rings boundvianitrogen to the distal ethane carbon of methoxy ethane. The dihedral angles between the three pyrazole rings are 67.62 (14), 73.74 (14), and 78.92 (12)°. In the crystal, molecules are linked by bifurcated C—H,H...N hydrogen bonds, forming double-stranded chains along [001]. The chains are linkedviaC—H...O hydrogen bonds, forming a three-dimensional framework structure. The crystal was refined as a perfect (0.5:0.5) inversion twin.

Synthesis, crystal structures and luminescence properties of lanthanide oxalatophosphonates with a three-dimensional framework structure

2009 ◽  
Vol 33 (1) ◽  
pp. 119-124 ◽  
Author(s):  
Yanyu Zhu ◽  
Zhengang Sun ◽  
Yan Zhao ◽  
Jing Zhang ◽  
Xin Lu ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Three Dimensional ◽  
Luminescence Properties ◽  
Framework Structure

scholarly journals Crystal structure of (E)-1,3-dimethyl-2-[3-(3-nitrophenyl)triaz-2-en-1-ylidene]-2,3-dihydro-1H-imidazole

2014 ◽  
Vol 70 (10) ◽  
pp. 224-227 ◽  
Author(s):  
Siddappa Patil ◽  
Alejandro Bugarin
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Three Dimensional ◽  
Imidazole Ring ◽  
Asymmetric Unit ◽  
Framework Structure ◽  
Compound C ◽  
Centroid Distance ◽  
Independent Molecules

The title compound, C11H12N6O2, a π-conjugated triazene, crystallized with two independent molecules (AandB) in the asymmetric unit. Both molecules have anEconformation about the –N=N– bond and have slightly twisted overall conformations. In moleculeA, the imidazole ring is inclined to the benzene ring by 8.12 (4)°, while in moleculeBthe two rings are inclined to one another by 7.73 (4)°. In the crystal, the independent molecules are linked to each other by C—H...O hydrogen bonds, forming –A–A–A– and –B–B–B–chains along [100]. The chains are linked by C—H...O and C—H...N hydrogen bonds, forming sheets lying parallel to (001). The sheets are linked by further C—H...N hydrogen bonds and π–π interactions [centroid–centroid distance = 3.5243 (5) Å; involving the imidazole ring of molecule A and the benzene ring of moleculeB], forming a three-dimensional framework structure.

scholarly journals (NH4)Mg(HSO4)(SO4)(H2O)2 and NaSc(CrO4)2(H2O)2, two crystal structures comprising kröhnkite-type chains, and the temperature-induced phase transition (NH4)Mg(HSO4)(SO4)(H2O)2\rightleftharpoons (NH4)MgH(SO4)2(H2O)2

2021 ◽  
Vol 77 (3) ◽  
pp. 144-151
Author(s):  
Matthias Weil ◽  
Uwe Kolitsch
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Room Temperature ◽  
Classification Scheme ◽  
Three Dimensional ◽  
Structure Type ◽  
Group Symmetry ◽  
Water Molecules

The crystal structure of the mineral kröhnkite, Na2Cu(SO4)2(H2O)2, contains infinite chains composed of [CuO4(OH2)2] octahedra corner-linked with SO4 tetrahedra. Such or similar tetrahedral–octahedral `kröhnkite-type' chains are present in the crystal structures of numerous compounds with the composition AnM(XO4)2(H2O)2. The title compounds, (NH4)Mg(HSO4)(SO4)(H2O)2, ammonium magnesium hydrogen sulfate sulfate dihydrate, and NaSc(CrO4)2(H2O)2, sodium scandium bis(chromate) dihydrate, are members of the large family with such kröhnkite-type chains. At 100 K, (NH4)Mg(HSO4)(SO4)(H2O)2 has an unprecedented triclinic crystal structure and contains [MgO4(OH2)2] octahedra linked by SO3(OH) and SO4 tetrahedra into chains extending parallel to [\overline{1}10]. Adjacent chains are linked by very strong hydrogen bonds between SO3(OH) and SO4 tetrahedra into layers parallel to (111). Ammonium cations and water molecules connect adjacent layers through hydrogen-bonding interactions of medium-to-weak strength into a three-dimensional network. (NH4)Mg(HSO4)(SO4)(H2O)2 shows a reversible phase transition and crystallizes at room temperature in structure type E in the classification scheme for structures with kröhnkite-type chains, with half of the unit-cell volume for the resulting triclinic cell, and with disordered H atoms of the ammonium tetrahedron and the H atom between two symmetry-related sulfate groups. IR spectroscopic room-temperature data for the latter phase are provided. Monoclinic NaSc(CrO4)2(H2O)2 adopts structure type F1 in the classification scheme for structures with kröhnkite-type chains. Here, [ScO4(OH2)2] octahedra (point group symmetry \overline{1}) are linked by CrO4 tetrahedra into chains parallel to [010]. The Na+ cations (site symmetry 2) have a [6 + 2] coordination and connect adjacent chains into a three-dimensional framework that is consolidated by medium–strong hydrogen bonds involving the water molecules. Quantitative structural comparisons are made between NaSc(CrO4)2(H2O)2 and its isotypic NaM(CrO4)2(H2O)2 (M = Al and Fe) analogues.

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