A REFINEMENT OF THE CRYSTAL STRUCTURES OF (NH4)2TeBr6 AND Cs2TeBr6

1966 ◽  
Vol 44 (8) ◽  
pp. 939-943 ◽  
Author(s):  
A. K. Das ◽  
I. D. Brown
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Bromine Atom ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Anisotropic Temperature ◽  
Temperature Factors

(NH4)2TeBr6 and Cs2TeBr6 crystals have the cubic K2PtCl6 structure with space group: [Formula: see text] with a0 = 10.728 ± 0.003 Å and 10.918 ± 0.002 Å respectively. The positional coordinate of the bromine atom, and the anisotropic temperature factors of all atoms in the unit cell, have been refined for both crystals by a full matrix least-squares analysis of the three dimensional X-ray diffraction data (R = 0.08). The Te—Br distance, corrected for probable thermal motions of atoms forming the bond, is 2.70 ± 0.01 Å in both crystals.

The Flavonoids of Combretum quadrangulare: Crystal structures of the Polymorphic Forms of 5-Hydroxy-2-(4'-hydroxy-3',5'-dimethoxyphenyl)-3,7-dimethoxy-4H-1-benzopyran-4-one

1985 ◽  
Vol 38 (8) ◽  
pp. 1177 ◽  
Author(s):  
IR Castleden ◽  
SR Hall ◽  
S Nimgirawath ◽  
S Thadaniti ◽  
AH White
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Β Phase ◽  
Α Phase ◽  
Polymorphic Forms

The following substituted 2-phenyl-4H-1-benzopyran-4-ones have been isolated from the dried flowers of Combretum quadrangulare Kurz ( Combretaceae ): 5-hydroxy-3,3′,4′,5′,7-pentamethoxy ( combretol ) (1), 3′,5-dihydroxy-3,4′,7-trimethoxy ( ayanin ) (2) and 4′,5-dihydroxy- 3,3′,5′,7-tetramethoxy (3). The last substance (3) was obtained as a mixture of two polymorphic forms (α and β) each of which was characterized by X-ray diffraction. Diffractometer data at 295 K were refined by full matrix least squares to residuals of 0.043 (1181 'observed' reflections) for the α-phase and 0.044 (1421) for the β phase of (3). Crystals of the α-phase of (3) are triclinic, Pī, a 12.663(6), b 9.592(4), c 7.444(4) Ǻ, α 102.48(3), β 101.39(4), γ 91.72(4)°,Z 2. Crystals of the β-phase of (3) are monoclinic P21/n, a 17.139(8), b 12.728(6), c 7.845(7) Ǻ, β 95.07(6)°, Z 4. An unambiguous synthesis of (3) was also achieved.

scholarly journals Crystal structure of Tetraaqua(ethylenediamine)nickel(II) sulfate dihydrate and of Tetraaqua(2,2'-bipyridyl)nickel(II) sulfate dihydrate

1984 ◽  
Vol 37 (5) ◽  
pp. 921 ◽  
Author(s):  
PC Healy ◽  
JM Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Single Crystal ◽  
Least Squares ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Oxygen Atoms

The crystal structures of the title compounds, [Ni(OH2)4(en)] [SO4].2H2O, (1), and [Ni(OH2)4(bpy)]- [SO4].2H2O, (2), have been determined by single-crystal X-ray diffraction methods at 295 K, being refined by full matrix least-squares methods to residuals of 0.028,0.031 for 1852, 4323 independent 'observed' reflections respectively. Crystals of (1) are monoclinic, C2/c, a 9.459(4), b 12.192(7), c 12.294(3) �, β 119.84(4)�, Z 4. In the cation, Ni-N is 2.061(2) �; Ni-O (trans to O, N respectively) are 2.106(2), 2.063(2) �. Instead of being enlarged above 90� as predicted from repulsion theory, the angle between the pair of oxygen atoms trans to nitrogen is diminished, being 87 14(7)�. Crystals of (2) are triclinic, P1, a 11.476(5), b 9.351(5), c 7.793(4) �, α 77.63(4), β 83.52(3), γ87.40(4)�, Z 2. In the cation, Ni-N are both 2.063(2) �. Ni-O (trans to N, O respectively) are 2.060(2), 2.O42(2); 2.O80(2), 2�. The short Ni-O distance [2.042(2)�] is associated with the coordination of a trigonal water molecule.

The crystal structure of galeite, Na15(SO4)5F4Cl

1975 ◽  
Vol 40 (312) ◽  
pp. 357-361 ◽  
Author(s):  
L. Fanfani ◽  
A. Nunzi ◽  
P. F. Zanazzi ◽  
A. R. Zanzari
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Thermal Parameters ◽  
X Ray Diffraction ◽  
Cell Content ◽  
X Ray ◽  
Structure Factors

SummaryThe crystal structure of galeite from Searles Lake (California) has been determined by means of X-ray diffraction data on a single crystal. A possible structure was derived from that of schairerite on the basis of chemical and lattice analogies and was confirmed by comparison of the observed diffractometric structure factors with the calculated ones. The refinement was performed by least-squares methods employing isotropic thermal parameters and assuming that atoms related by translational pseudosymmetry exhibit equal thermal parameters. The final R value is 0·09. The cell content is 3[Na15(SO4)5F4Cl]; the space group is P31m The lattice dimensions are a 12·197(4)Å, c 13·955(10) Å The marked subcell has P3m1 symmetry and a 7·042Å, c 13·955 Å. The crystal structure of galeite consists of a three-dimensional framework, formed by coordination octahedra around Na+ ions, including tetrahedral holes with sulphur atoms at the centres. The three-dimensional framework can be considered built up by five octahedral sheets (seven sheets can be recognized in schairerite and six in sulphohalite). The very close analogies occurring in the structures of galeite and schairerite are discussed.

Crystal structures of (RS)-Di-μ-chloro-tetrakis(ethane-1,2-diamine)nickel(II) dichloride and diperchlorate

1978 ◽  
Vol 31 (2) ◽  
pp. 285 ◽  
Author(s):  
GA Bottomley ◽  
LG Glossop ◽  
CL Raston ◽  
AH White ◽  
AC Willis
Keyword(s):  
Single Crystal ◽  
Least Squares ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Complex Cation ◽  
Dimeric Complex ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coordination Sites

The crystal structures of [(en)2NiCl2Ni(en)2] Cl2 (1) and [(en)2NiCl2Ni(en)2] (ClO4)2 (2) have been redetermined from single- crystal X-ray diffraction data at 295(1) K and refined by least squares to residuals of 0.073 and 0.052 respectively for 1345 and 1605 'observed' reflections respectively. Crystals of (1) are monoclinic, P21/n, a 14.053(4), b 11.309(3), c 6.326(1) Ǻ, β 94.22(2)�, Z 2. Crystals of (2) are monoclinic, P21/n, a 8.885(12), 6 19.707(20), c 7.120(8) Ǻ, β 108.99(4)�, Z 2. In both (1) and (2), a dimeric complex cation is observed, a pair of cis coordination sites about the nickel in each case being occupied by the bridging chlorines; the latter are asymmetric (Ni-Cl, 2.461(3), 2.551(3)(1); 2.461(3), 2.512(3) Ǻ (2)).

The Crystal-Structures of (±)-(E)-2-(1-Amino-Ethylidene)-4,4,6-Trimethylcyclohexane-1,3-Dione [(±)-Aminoangustione] and (E)-2-(1-Aminoethylidene)-4,6,6-Trimethylcyclohex-4-Ene-1,3-Dione (Aminodehydroangustione)

1986 ◽  
Vol 39 (6) ◽  
pp. 923 ◽  
Author(s):  
JR Cannon ◽  
VA Patrick ◽  
AH White
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray

The crystal structures of (�)-(E)-2-(1-aminoethylidene)-4,4,6- trimethylcyclohexane-1,3-dione [(�)- aminoangustione ] (8) and (E)-2-(1- aminoethylidene )-4,6,6-trimethylcyclohex-4-ene-1,3-dione ( aminodehydroangustione ) (9) have been determined by X-ray diffraction. Diffractometer data at 295 K were refined by full-matrix least-squares to residuals of 0.057 (712 'observed' reflections) for (8) and 0.061 (571) for (9). Crystals of (8) are tetragonal I 41/a, a 21.68(1), c 9.426(6)Ǻ, Z 16; crystals of (9) are orthorhombic Pmab , a 7.077(2), b 11.421(6), c 13.283(4)Ǻ, Z 4.

Crystal structures of trans-Dichloro- and Dibromo-bis(2,6-dimethylpyridine)copper(II)

1977 ◽  
Vol 30 (9) ◽  
pp. 1947 ◽  
Author(s):  
JA Campbell ◽  
CL Raston ◽  
JN Varghese ◽  
AH White
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
Compound A ◽  
Full Matrix ◽  
X Ray ◽  
Square Planar

The crystal structures of the title compounds have been determined at 295(1) K by X-ray diffraction and refined by full-matrix least squares to residuals of 0.045 and 0.067 for 1224 and 1955 ?observed? reflections respectively. The compounds are isomorphous (triclinic, Pī, Z 1). Dichloro compound: a 8.068(2), b 8.024(2), c 7.646(2) Ǻ, α 93.84(2), β 113.44(2), γ 117.11(2)�. Dibromo compound: a 7.999(2), b 7.921(2), c 7.849(2) Ǻ, α 94.37(2), β 112.85(2), γ 115.99(2)�. The copper atoms are square-planar coordinated with two halide and two base ligands coordinated necessarily trans by virtue of the siting of the molecule on a centre of symmetry. Cu-X, Cu-N are 2.264(2), 2.011(3) (dichloro); 2.425(1), 1.997(4) Ǻ (dibromo). The plane of the lutidine is almost normal to the CuN2X2 plane.

Structure refinements of seven natural olivine crystals and the influence of the oxygen partial pressure on the cation distribution

1981 ◽  
Vol 155 (1-2) ◽  
Author(s):  
G. Nover ◽  
G. Will
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Extinction Coefficient ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Volcanic Origin ◽  
X Ray ◽  
Anisotropic Temperature ◽  
Natural Olivine ◽  
Temperature Factors

AbstractMg/Fe order in olivine has been determined by X-ray diffraction data, for example by Wenk and Raymond (1973). We have now studied the dependence of the Mg/Fe order vs. oxygen partial pressure. Two natural olivine samples of volcanic origin containing respectively 10 and 12 % fayalite were selected. The atomic positions, anisotropic temperature factors, extinction coefficient and site occupancies have been refined toThese experiments seem to indicate that the prevailing oxygen partial pressure determines the different Mg/Fe order found in natural olivine crystals.

The crystal structure of BiTel

1993 ◽  
Vol 204 (1) ◽  
Author(s):  
K. G. Keramidas ◽  
G. P. Voutsas ◽  
A. Papazoglou ◽  
P. I. Rentzeperis
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Three Dimensional ◽  
Full Matrix ◽  
Anisotropic Temperature ◽  
Equilateral Triangles ◽  
Computer Controlled ◽  
Temperature Factors ◽  
Isosceles Triangles

AbstractThe crystal structure of BiTeI has been redetermined with 1924 independent reflections, using three-dimensional intensities measured on a computer controlled Philips PW 1100 single crystal diffractometer. The structure belongs to the rhombohedral space groupThe positional and thermal parameters, with anisotropic temperature factors, were refined by full-matrix least-squares calculations to a finalEach Bi atom is six-coordinated by three Te and three I atoms at distances 3.88(5) Å and 3.05(2) Å respectively thus forming a distorted octahedron. The faces of the octahedron are two equilateral triangles (Te-Te-Te, I-I-I) with sides 4.336 Å and six isosceles triangles (three I-Te-I and three Te-I-Te) with sides I–Te 3.29(3) Å and I–I or Te–Te 4.336 Å.The octahedra are linked to each other by a common Te–I edge along the

Crystal structures of o-phenylenediarsine oxychloride (a redetermination) and o-phenylenediarsine oxybromide

1975 ◽  
Vol 28 (1) ◽  
pp. 15 ◽  
Author(s):  
JC Dewan ◽  
K Henrick ◽  
AH White ◽  
SB Wild
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
Space Group ◽  
X Ray ◽  
Limits Of Error

The crystal structures of the title compounds have been established by X-ray diffraction at 295 K, being refined by full-matrix least-squares to residuals of 0.054 (0.051) respectively 2715 (469) reflections with I > σ(I)]. Crystals are monoclinic, space group C2/c, the compounds being isomorphous. Oxychloride: a = 14.534(4), b = 8.337(2), c = 7.653(1)Ǻ, β = 106.48(1)�. Oxybromide: a = 14.884(4), b = 8.360(2), c = 7.726(1)Ǻ, β = 105.30(1)�, Z = 4. With the exception-of the arsenic- halogen distance, the geometries of the two molecules are identical within the limits of error: for the oxychloride As-O-As, 121.8(3); Cl- As-O,98.03(6); Cl-As-C, 97.2(2); O-As-C, 92. 9(2)� ; As-O, 1.787(3); As-C, 1.941(5) Ǻ. As-Cl is 2.222(2) and As-Br 2.381(2) Ǻ.

Crystal structure of (1,7,8,9-η-Bicyclo[5,2,0]nona-1(7),2,5,8-tetraen-4-one)tricarbonyliron(0)

1978 ◽  
Vol 31 (7) ◽  
pp. 1619 ◽  
Author(s):  
SR Hall ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Diffraction Data ◽  
Iron Atom ◽  
Title Compound ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray

The crystal structure of the title compound, [Fe(CO)3(C9H6O)], has been determined from single-crystal X-ray diffraction data at 295 K and refined by full-matrix least squares to a residual of 0.039 (2160 'observed' reflections). Crystals are monoclinic, P21/c, a 9.326(5), b 12.293(5), c 10.342(4) Ǻ, β 115.77(3)°, Z 4. The iron atom is symmetrically bound to the four atoms of the cyclobutadiene ring (<Fe- C> 2.055 Ǻ).

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