The crystal structure of zigrasite, MgZr(PO4)2(H2O)4, a heteropolyhedral framework structure

2010 ◽  
Vol 74 (3) ◽  
pp. 567-575 ◽  
Author(s):  
F. C. Hawthorne ◽  
W. B. Simmons

AbstractThe crystal structure of zigrasite, ideally MgZr(PO4)2(H2O)4, a 5.3049(2), b 9.3372(4), c 9.6282(5) Å, α 97.348(1)°, β 91.534(1)°, γ 90.512(4)°, V 472.79(5) Å3, Z = 2, triclinic, P1, Dcalc. 2.66 g.cm–3, from the giant 1972 pocket at Newry, Oxford County, Maine, USA, has been solved and refined to R1 3.75% on the basis of 2623 unique reflections (Fo > 4σF). There are two P sites, each of which is solely occupied by P with <P–O> distances of 1.532 and 1.533 Å, respectively. There are two Mg sites, both of which are occupied by Mg and are octahedrally coordinated two O anions and four (H2O) groups with <Mg–O> distances of 2.064 and 2.075 Å, respectively. There is one Zr site, occupied by Zr and octahedrally coordinated by six O anions with a <Zr–O> distance of 2.065 Å . The (ZrO6) octahedron shares corners with six (PO4) tetrahedra, forminga [Zr(PO4)2] sheet parallel to (001). These sheets are stacked in the c direction and linked by (MgO2(H2O)4) octahedra that share O atoms with the (PO4) groups. The structure is formally a heteropolyhedral framework structure, but the linkage is weaker in the c direction, accounting for the marked (001) cleavage.

2001 ◽  
Vol 65 (2) ◽  
pp. 297-304 ◽  
Author(s):  
Yaping Li ◽  
S. V. Krivovichev ◽  
P. C. Burns

AbstractCrystals of the compound Na4(UO2)(CO3)3 have been synthesized and the structure has been solved. It is trigonal with a= 9.3417(6), c = 12.824(1) Å, V = 969.2(1) Å3, space group P3̄c1 and Z = 4. The structure was refined on the basis of F2 (wR2 = 4.2%) for all unique data collected using Mo-Kα X-radiation and a CCD-based detector. The final R1 was 2.0%, calculated for 534 unique observed (Fo ≥ 4σF) reflections, and the goodness-of-fit (S) was 0.91. The structure contains a uranyl tricarbonate cluster composed of a uranyl hexagonal bipyramid that shares three equatorial edges with CO3 triangles. The uranyl tricarbonate clusters are connected through NaO6 and NaO5 polyhedra, forming a heteropolyhedral framework structure. This compound may be related to a uranyl carbonate phase with the same composition which has been reported as an alteration phase on the surface of Chernobyl ‘lava’, and as a mineral in the Jachymov ore district, Czech Republic.


Author(s):  
Matthias Weil ◽  
Théo Veyer

A new form of NaMnAsO4, sodium manganese(II) orthoarsenate, has been obtained under hydrothermal conditions, and is referred to as the β-polymorph. In contrast to the previously reported orthorhombic α-polymorph that crystallizes in the olivine-type of structure and has one manganese(II) cation in a distorted octahedral coordination, the current β-polymorph contains two manganese(II) cations in [5]-coordination, intermediate between a square-pyramid and a trigonal bipyramid. In the crystal structure of β-NaMnAsO4, four [MnO5] polyhedra are linked through vertex- and edge-sharing into finite {Mn4O16} units strung into rows parallel to [100]. These units are linked through two distinct orthoarsenate groups into a framework structure with channels propagating parallel to the manganese oxide rows. Both unique sodium cations are situated inside the channels and exhibit coordination numbers of six and seven. β-NaMnAsO4 is isotypic with one form of NaCoPO4 and with NaCuAsO4.


2021 ◽  
Vol 66 (1) ◽  
pp. 60-65
Author(s):  
N. V. Zubkova ◽  
I. V. Pekov ◽  
A. A. Agakhanov ◽  
D. A. Ksenofontov ◽  
D. Yu. Pushcharovsky

2014 ◽  
Vol 70 (9) ◽  
pp. o1047-o1048 ◽  
Author(s):  
Ganna Lyubartseva ◽  
Sean Parkin ◽  
Morgan D. Coleman ◽  
Uma Prasad Mallik

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.


1980 ◽  
Vol 35 (6) ◽  
pp. 672-675 ◽  
Author(s):  
Chr. L. Teske

Abstract Ba2ZnGe2S6O was prepared for the first time and the crystal structure determined by using single crystal X-ray methods. The space group is D32d-P4̄21m, tetragonal (No. 113). Lattice constants: a = 963.59 ± 0.22; c = 645.06 ± 0.25 pm. The tetrahedral framework structure is described and discussed. Zn is linked only to sulfur. The oxygen belongs to the coordination sphere of Ge and Ba.


2010 ◽  
Vol 34 (11) ◽  
pp. 2429 ◽  
Author(s):  
Na Zhang ◽  
Zhengang Sun ◽  
Yanyu Zhu ◽  
Jing Zhang ◽  
Lei Liu ◽  
...  

2002 ◽  
Vol 58 (2) ◽  
pp. 198-218 ◽  
Author(s):  
G. D. Ilyushin ◽  
V. A. Blatov

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.


Author(s):  
Ghaleb Alhakmi ◽  
Abderrazzak Assani ◽  
Mohamed Saadi ◽  
Lahcen El Ammari

The title compound, Mn2Zn(PO4)2·H2O, was obtained under hydrothermal conditions. The structure is isotypic with other transition metal phosphates of the typeM3−xM′x(PO4)2·H2O, but shows no statistical disorder of the three metallic sites. The principal building units are distorted [MnO6] and [MnO5(H2O)] octahedra, a distorted [ZnO5] square pyramid and two regular PO4tetrahedra. The connection of the polyhedra leads to a framework structure. Two types of layers parallel to (-101) can be distinguished in this framework. One layer contains [Zn2O8] dimers linked to PO4tetrahedraviacommon edges. The other layer is more corrugated and contains [Mn2O8(H2O)2] dimers and [MnO6] octahedra linked together by common edges. The PO4tetrahedra link the two types of layers into a framework structure with channels parallel to [101]. The H atoms of the water molecules point into the channels and form O—H...O hydrogen bonds (one of which is bifurcated) with framework O atoms across the channels.


ChemInform ◽  
2010 ◽  
Vol 29 (44) ◽  
pp. no-no
Author(s):  
M. J. MACLACHLAN ◽  
S. PETROV ◽  
R. L. BEDARD ◽  
I. MANNERS ◽  
G. A. OZIN

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