REFINEMENT OF THE CRYSTAL STRUCTURE OF β-Mg2P2O7

1965 ◽  
Vol 43 (5) ◽  
pp. 1139-1146 ◽  
Author(s):  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Bond Angle ◽  
Analysis Data ◽  
Thermal Motion ◽  
Infrared Studies ◽  
Central Oxygen ◽  
Atomic Parameters

The crystal structure of Mg2P2O7 reported by Lukaszewicz has been refined by least squares analysis. Data of the hkl type with O ≤ k ≤ 6 have been used to obtain improved atomic parameters. The central oxygen atom of the P2O7−4 is found to have enhanced thermal motion in the plane perpendicular to the P—P vector. Thus the P—O—P bond angle appears to be linear in this phase because of a thermal averaging of the position of the central oxygen atom. This conclusion is in agreement with that obtained by Lazarev from infrared studies.

THE CRYSTAL STRUCTURE AND PHASE TRANSITIONS OF β-Zn2P2O7

1965 ◽  
Vol 43 (5) ◽  
pp. 1147-1153 ◽  
Author(s):  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Oxygen Atom ◽  
Bond Angle ◽  
Thermal Motion ◽  
Mirror Plane ◽  
Red Emission ◽  
Space Group ◽  
Central Oxygen ◽  
Cation Coordination

β-Zn2P2O7 crystallizes in the C2/m space group with lattice parameters a = 6.61 ± 0.01 Å, b = 8.29 ± 0.01 Å, c = 4.51 ± 0.01 Å, β = 105.4° ± 0.2° and z = 2. The anion, P2O7−4, is centered with its mirror plane coinciding with the mirror plane of the space group. The central oxygen atom, however, shows high anisotropic thermal motion and thus it appears that the P—O—P bond angle is linear only as a result of thermal averaging. The cations are found on twofold axes in irregular sixfold coordination and these ZnO6 groups share three edges with neighboring cations. This cation coordination is, therefore, consistent with that predicted from the red emission of β-Zn2P2O7:Mn++.

Refinement of the structure of Mg2As2O7

1970 ◽  
Vol 48 (6) ◽  
pp. 890-894 ◽  
Author(s):  
C. Calvo ◽  
K. Neelakantan
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Unit Cell ◽  
Full Matrix ◽  
Space Group ◽  
Cell Dimensions ◽  
Central Oxygen ◽  
R Value ◽  
Unit Cell Dimensions

The crystal structure of Mg2As2O7 has been refined by full matrix least squares procedures using 587 observed reflections. The structure of Mg2As2O7 is of the thortveitite type, as reported by Łukaszewicz, with space group C2/m and unit cell dimensions a = 6.567(2) Å, b = 8.524(4) Å, c = 4.739(1) Å, β = 103.8(1)°, and Z = 2. The As—O—As group in the anion appears to be linear but the central oxygen atom undergoes considerable disorder in the plane perpendicular to this group. The AsO bond distances uncorrected for thermal motion are 1.67 Å for the As—O(—As) bond and 1.66 and 1.65 Å for the terminal As—O bonds. The final R value obtained is 0.088.

scholarly journals Conformations of Bridged Diphenyls. II. Crystal Structure of 2-(2′,4′-Dinitrophenoxy)-1,3,5-tri-t-butylbenzene

1972 ◽  
Vol 50 (18) ◽  
pp. 2972-2978 ◽  
Author(s):  
E. A. H. Griffith ◽  
W. D. Chandler ◽  
B. E. Robertson
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Bond Angle ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ether Oxygen Atom ◽  
Phenyl Rings ◽  
Ether Oxygen

The structure of 2-(2′,4′-dinitrophenoxy)-1,3,5-tri-t-butylbenzene, C24H32N2O5, has been determined by X-ray diffraction. The crystals are triclinic, a = 12.160(30), b = 10.564(17), c = 10.684(16) Å, α = 119.23(10), β = 96.06(15), γ = 96.55(15)°, [Formula: see text] with Z = 2. The intensities of 5359 independent reflections were measured on a four circle diffractometer of which 2471 were used in the refinement to give a final least-squares weighted residue of 0.063. The presence of two electron withdrawing groups on one of the phenyl rings increases the conjugation between the ring and the ether oxygen atom to a greater degree than was found in the previous work. The tri-t-butyl-substituted ring is nearly orthogonal to the other ring. The bond angle at the ether oxygen atom is less than the value found earlier but ring distortions are similar.

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.

Darstellung und Kristallstruktur von Lithiumozonid-Ammoniakat (1/5) LiO3 · 5 NH3/Synthesis and Crystal Structure of Lithiumozonide-Ammonia (1/5) LiO3 · 5 NH3

1999 ◽  
Vol 54 (11) ◽  
pp. 1345-1349 ◽  
Author(s):  
Wilhelm Klein ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Cation Exchange ◽  
Liquid Ammonia ◽  
Boiling Temperature ◽  
Synthesis And Crystal Structure ◽  
Central Oxygen

Lithium ozonide has been synthezised starting from cesium ozonide via cation exchange in liquid ammonia and crystallizes at -78°C as an ammoniate, LiO3 · 5NH3. The coarse, ruby red crystals decompose above the boiling temperature of ammonia and are extremely sensitive to moisture. The crystal structure of L iO3 · 5NH3 (P c21n; a = 1231.9(5), b = 637.4(2), c = 1104.8(4) pm; Z = 4; R1 = 4.57%; 1318 independent reflections) consists of lithium tetramine complexes, ozonide anions and non coordinating ammonia molecules. With respect to the arrangement of the complex cations and of the anions there is similarity to the WC type of structure. The central oxygen atom of the ozonide anion is disordered.

Crystal structure of Tetracyclo[5,3,1,12,6,04,9]dodecane (iceane)

1977 ◽  
Vol 30 (8) ◽  
pp. 1837 ◽  
Author(s):  
DPG Hamon ◽  
CL Raston ◽  
GF Taylor ◽  
JN Varghese ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Rigid Body ◽  
Least Squares ◽  
Title Compound ◽  
Molecular Geometry ◽  
Thermal Motion ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Hexagonal Close Packed

The crystal structure of the title compound, C12H18, has been determined at 295 K by X-ray diffraction and refined by full-matrix least squares to a residual of 0.049 for 216 ?observed? reflections; molecular geometry has been corrected for the effects of thermal motion using a rigid body approximation. Crystals are hexagonal, P63/m, a = 6.582(1), c = 11.843(3) Ǻ, Z = 2, the molecules occupying a hexagonal close- packed array.

Crystal structure of Tris(ethane-1,2-diamine)nickel(II) diperchlorate monohydrate

1978 ◽  
Vol 31 (2) ◽  
pp. 415 ◽  
Author(s):  
CL Raston ◽  
AH White ◽  
AC Willis
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Diffraction Data ◽  
Structure Determination ◽  
Title Compound ◽  
Thermal Motion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Very High

The crystal structure of the title compound, [Ni(en)3] (ClO4)2,H2O, has been determined from single-crystal X-ray diffraction data at 295(1) K and refined by least squares to a residual of 0.093 for 1400 'observed' reflections. Crystals are orthorhombic, P bca, a 17.043(7), b 15.922(6), c 13.496(5) Ǻ, Z 8. The precision of the structure determination is adversely affected by very high perchlorate thermal motion. <Ni-N> is 2.13 Ǻ.

Crystal Structure of α-VPO5

1973 ◽  
Vol 51 (16) ◽  
pp. 2621-2625 ◽  
Author(s):  
Byron Jordan ◽  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Least Squares Method ◽  
Fold Axis ◽  
Full Matrix ◽  
Bond Lengths ◽  
R Value ◽  
A Site ◽  
Vanadium Ion

α-VPO5 crystallizes in the tetragonal space group P4/n with a = 6.014(7) and c = 4.434(2) Å. The structure, isotypic with that of α-VSO5, was refined by full-matrix least-squares method to an R value of 0.089 using 239 independent reflections. The vanadium ion lies on a crystallographic four-fold axis, as does one of the oxygen atoms, and the P on a site of [Formula: see text] symmetry. A second oxygen atom, as a result of disorder, occurs in two positions which are mirror reflected with respect to the ac plane. The structure consists of highly distorted VO6 groups with bond lengths along the c axis of 1.580(11) and 2.853(11) Å while the remaining four V—O bond lengths are all 1.858(8) Å. The P—O bond lengths in the PO4. tetrahedron are 1.541(8) Å with the PO4 groups bridging across four chains of VO6 groups.

Crystal structure of Cd2V2O7

1967 ◽  
Vol 45 (20) ◽  
pp. 2297-2302 ◽  
Author(s):  
P. K. L. Au ◽  
C. Calvo
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Lattice Parameters ◽  
The Other ◽  
Distorted Octahedron ◽  
Thermal Activity ◽  
Space Group ◽  
Bond Angles ◽  
Central Oxygen ◽  
Oxygen Atoms

Cadmium pyrovanadate crystallizes in the C2/m space group with lattice parameters a = 7.088(5) Å, b = 9.091(5) Å, c = 4.963(5) Å, β = 103°21(5)′, and z = 2. This crystal is an isostructure of the mineral thortveitite and thus the anion consists of a pair of centrosymmetrically related corner-sharing VO4 tetrahedra while the cation resides within a distorted octahedron of oxygen atoms. The anion has a linear V—O—V group, but, as with the isostructural pyrophosphates, the central oxygen atom shows an anomalously high thermal activity. The V—O bond distances are 1.76 Å for the inner bond and 1.70 Å for the terminal bond. The bond angles about the anion and cation are similar to those found for the other analogues of thortveitite.

Preparation and Crystal Structure of Hexapotassium-μ-Oxo-Hexathiodititanate(IV), K6Ti2OS6

2003 ◽  
Vol 58 (1) ◽  
pp. 163-167 ◽  
Author(s):  
Kurt O. Klepp ◽  
Ferdinand Fabian
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Title Compound ◽  
Bond Angle ◽  
Tetrahedral Configuration ◽  
Bond Lengths ◽  
Pale Yellow ◽  
Intimate Mixture ◽  
The Mean ◽  
Complex Anions

Abstract Pale yellow crystals of the title compound were obtained by reacting an intimate mixture of K2S, K2S2O4, Ti and S at 650 °C. K6Ti2OS6 is monoclinic, mP60, s. g. P21/c. It is characterized by the formation of bitetrahedral complex anions, [S3TiOTiS3]6−, which adopt a staggered conformation. The mean Ti-S and Ti-O bond lengths are 2.242(1) and 1.836(2) Å , respectively, the Ti-O-Ti bond angle is 153.8(2)°. Two K+ ions complete the coordination of the bridging oxygen atom by the cations to a heavily distorted tetrahedral configuration. The anions are arranged in corrugated slabs running parallel to (100). The packing and crystallographic relationship to K6Co2O7 are discussed.

Sign in / Sign up

Export Citation Format

Share Document