The crystal structure of tetraethylammonium Tris(O-ethylxanthato)tellurate(II): An example of five-coordinate pentagonal-planar geometry

1976 ◽  
Vol 29 (11) ◽  
pp. 2337 ◽  
Author(s):  
BF Hoskins ◽  
CD Pannan
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Three Dimensional ◽  
Planar Geometry ◽  
Maximum Deviation ◽  
Valence Shell ◽  
X Ray Diffraction ◽  
Electron Pairs ◽  
Fourier Methods ◽  
X Ray

The crystal structure of tetraethylammonium tris(O-ethylxanthato) tellurate(11), [Et4N] [Te(S2COEt)3], has been determined by single-crystal three-dimensional X-ray diffraction methods. Crystals are monoclinic of space group P21/c with four cation-anion pairs per unit cell which has the dimensions a 8.121(1), b 18.858(2), c 19.260(2) � and β 105.22(2)�. The structure was solved by the normal Fourier methods and was refined with anisotropic thermal parameters by a full-matrix least-squares method converging with R and Rw values of 0.061 and 0.082 for the 2404 independent statistically significant reflections collected by counter methods. The tris(ethylxanthato)tellurate(11) anion has a novel five-coordinate pentagonal-planar structure with only two of the xanthato ligands bidentate and with the Te-S bond distances having values in the range 2.503(4)-3.059(3)�. The TeS5 atoms are coplanar, the maximum deviation from the plane being 0.122 �. This, together with the intra-planar S...S distances of 3.340-3.661 �, indicates that the ligand atoms of the pentagonal plane are not over-crowded. The geometry of the anion configuration can be explained in terms of the VSEPR theory using a pentagonal-bipyramidal arrangement of the seven electron pairs in the valence shell of the tellurium.

scholarly journals X-ray diffraction studies of enkephalins. Crystal structure of [(4′-bromo) Phe4,Leu5]enkephalin

1984 ◽  
Vol 218 (3) ◽  
pp. 677-689 ◽  
Author(s):  
T Ishida ◽  
M Kenmotsu ◽  
Y Mino ◽  
M Inoue ◽  
T Fujiwara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Heavy Atom ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Biologically Active ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relationship Of

In order to investigate the structure-activity relationship of [Leu5]- and [Met5]enkephalins, [(4′-bromo)Phe4, Leu5]-, [(4′-bromo)Phe4, Met5]- and [Met5] enkephalins were synthesized and crystallized. The crystal structure of [(4′-bromo) Phe4, Leu5]- enkephalin was determined by X-ray diffraction method using the heavy atom method and refined to R = 0.092 by the least-squares method. The molecule in this crystal took essentially the same type I' beta-turn conformation found in [Leu5]enkephalin [Smith & Griffin (1978) Science 199, 1214-1216). On the other hand, the preliminary three-dimensional Patterson analyses showed that the most probable conformations of [(4′-bromo)Phe4,Met5]- and [Met5]enkephalins are both the dimeric extended forms. Based on these insights, the biologically active conformation of enkephalin was discussed in relation to the mu- and delta-receptors.

A novel carbonyl bridging mode: the structure of the metal carbonyl complex [Mn2(CO)5(Ph2PCH2PPh2)2]

1975 ◽  
Vol 28 (8) ◽  
pp. 1663 ◽  
Author(s):  
CJ Commons ◽  
BF Hoskins
Keyword(s):  
Least Squares Method ◽  
Metal Carbonyl ◽  
Three Dimensional ◽  
Carbonyl Complex ◽  
X Ray Diffraction ◽  
Carbonyl Ligand ◽  
Fourier Methods ◽  
X Ray ◽  
Carbonyl Bond ◽  
Temperature Factors

The crystal structure of the solvated complex Mn2(CO)5(dpm)2,CH2Cl3,C6H14 (where dpm = Ph2PCH2PPh2) has been determined by three-dimensional X-ray diffraction methods. The crystals are monoclinic, of space group Cc, with a 19.650(3), b 16.908(2), c 22.253(4) Ǻ and β 130.89(1)�, containing four molecules per unit cell. The structure, solved by conventional Patterson and Fourier methods, was refined by a least- squares method, using individual isotropic temperature factors, to R and Rw of 0.105 and 0.125 respectively, for 1893 independent statistically significant reflections collected by counter methods. The crystals are molecular, being composed of discrete molecules of complex and solvent. The principal feature of interest in the binuclear manganese complex is the presence of a carbonyl ligand simultaneously bonded to both manganese atoms in a manner quite different from the normal symmetrical bridging mode. This novel arrangement, which seems to involve a metal-carbonyl bond analogous to that found for many metal-olefin complexes, accounts for the anomalously low carbonyl stretching frequency observed at 1645 cm-1. The Mn-Mn distance is 2.934(6) Ǻ.

Crystal and molecular structure of Octacarbonylbis(diphenylarsino)-methanedimanganese(0)

1983 ◽  
Vol 36 (4) ◽  
pp. 683 ◽  
Author(s):  
BF Hoskins ◽  
RJ Steen
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Parent Compound ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Fourier Methods ◽  
X Ray

The crystal structure of the complex Mn2(CO)8(dam) (dam = Ph2AsCH2AsPh2) has been determined by three-dimensional X-ray diffraction methods. The crystals are triclinic, space group P1, with a 11.191(1), b 16.498(5), c 9.455(1) �, a 93.64(2), β 109.08(2), γ 89.36(2)� and contain two discrete, binuclear molecules of Mn2(CO)8(dam) per unit cell. The structure, solved by direct and Fourier methods, was refined by a least-squares procedure to R and Rw of 0.065 and 0.082 respectively for 1907 independent, statistically significant reflections collected by counter methods. The feature of particular interest in this compound is the accommodation of the bridging bidentate dam ligand [As.. .As separation 3.242(2) �] across a shorter Mn�-Mn� bond [2.962(3) �] which constrains the molecule so that a much less staggered configuration of the two manganese coordination octahedra is observed relative to the parent compound Mn2(CO)10, the rotation of the two equatorial planes in the former being 30�.

scholarly journals Crystal structure and computational study of 2,4-dichloro-N-[(E)-(5-nitrothiophen-2-yl)methylidene]aniline

2016 ◽  
Vol 72 (8) ◽  
pp. 1187-1189 ◽  
Author(s):  
Yavuz Köysal ◽  
Hakan Bülbül ◽  
Sümeyye Gümüş ◽  
Erbil Ağar ◽  
Mustafa Serkan Soylu
Keyword(s):  
Crystal Structure ◽  
Computational Study ◽  
Three Dimensional ◽  
Maximum Deviation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compound C ◽  
Benzene Rings ◽  
The Mean ◽  
Good Agreement

The title compound, C11H6Cl2N2O2S, is a Schiff base that incorporates an N-bound 2,4-dichlorophenyl and a C-bound 5-nitrothiophene ring. The molecule is approximately planar, the maximum deviation from the mean plane being 0.233 (4) Å for the C=N N atom. The dihedral angle between the benzene and thiophene rings is 9.7 (2)°. The C=N double bond has anEconfiguration. The crystal structure features C—H...O hydrogen bonds,forming sheets parallel to (10-1), and π–π stacking interactions between symmetry-related thiophene and benzene rings, in which the distance between adjacent ring centroids is 3.707 (4) Å, forming a three-dimensional supramolecular structure. Geometric parameters from quantum-chemical calculations are in good agreement with experimental X-ray diffraction results.

Complexes of the dicyclohexylphosphinodithioformate anion involving the nickel triad metals: the crystal and molecular structures of the platinum(II) and palladium(II) derivatives

1984 ◽  
Vol 37 (1) ◽  
pp. 197 ◽  
Author(s):  
D Dakternieks ◽  
BF Hoskins ◽  
ERT Tiekink
Keyword(s):  
Phosphorus Atom ◽  
Least Squares Method ◽  
Central Atom ◽  
Three Dimensional ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Fourier Methods ◽  
Full Matrix ◽  
X Ray ◽  
Crystal And Molecular Structures

The crystal and molecular structures of bis (dicyclohexylphosphinodithioformato-S,P)M, M[S2CP-(C6Hl1)2]2 where M = Pt (1) and Pd (2), have been determined by single-crystal three-dimensional X-ray diffraction methods. The isomorphous crystals are monoclinic, of space group P21/c with four molecules per unit cell which has dimensions for (1) a 14.732(4), b 15.11 8(4), c 16.000(3) � and β 120.90(2)� and for (2) a 14.721(2), b 15.142(2), c 15.986(2) � and β 120.80(1)�. The structures were solved by normal Fourier methods and were refined with anisotropic thermal parameters. A full-matrix least-squares method was used, involving 3454 and 5052 statistically significant reflections for (1) and (2) respectively with final R and Rw values of 0.058 and 0.055 for (1) and 0.038 and 0.039 for (2). The complexes are isostructural. The ligand coordinates in a bidentate manner to the central atom through the phosphorus atom and one of the sulfur atoms with the metal atom in a cis-planar environment.

scholarly journals An investigation of polyhedral deformation in two mixed-metal diarsenates: SrZnAs2O7and BaCuAs2O7

2015 ◽  
Vol 71 (4) ◽  
pp. 330-337 ◽  
Author(s):  
Sabina Kovač ◽  
Ljiljana Karanović ◽  
Tamara Đorđević
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
General Formula ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Open Framework ◽  
Geometrical Characteristics ◽  
Barium Copper

Two isostructural diarsenates, SrZnAs2O7(strontium zinc diarsenate), (I), and BaCuAs2O7[barium copper(II) diarsenate], (II), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. The three-dimensional open-framework crystal structure consists of corner-sharingM2O5(M2 = Zn or Cu) square pyramids and diarsenate (As2O7) groups. Each As2O7group shares its five corners with five differentM2O5square pyramids. The resulting framework delimits two types of tunnels aligned parallel to the [010] and [100] directions where the large divalent nine-coordinatedM1 (M1 = Sr or Ba) cations are located. The geometrical characteristics of theM1O9,M2O5and As2O7groups of known isostructural diarsenates, adopting the general formulaM1IIM2IIAs2O7(M1II= Sr, Ba, Pb;M2II= Mg, Co, Cu, Zn) and crystallizing in the space groupP21/n, are presented and discussed.

The crystal structure of gatehouseite

2011 ◽  
Vol 75 (6) ◽  
pp. 2823-2832
Author(s):  
P. Elliott ◽  
A. Pring
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Three Dimensional ◽  
Direct Methods ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Manganese Phosphate ◽  
Phosphate Mineral ◽  
Unit Formula

AbstractThe crystal structure of the manganese phosphate mineral gatehouseite, ideally Mn52+(PO4)2(OH)4, space group P212121, a = 17.9733(18), b = 5.6916(11), c = 9.130(4) Å, V= 933.9(4) Å3, Z = 4, has been solved by direct methods and refined from single-crystal X-ray diffraction data (T = 293 K) to an R index of 3.76%. Gatehouseite is isostructural with arsenoclasite and with synthetic Mn52+(PO4)2(OH)4. The structure contains five octahedrally coordinated Mn sites, occupied by Mn plus very minor Mg with observed <Mn—O> distances from 2.163 to 2.239 Å. Two tetrahedrally coordinated P sites, occupied by P, Si and As, have <P—O> distances of 1.559 and 1.558 Å. The structure comprises two types of building unit. A strip of edge-sharing Mn(O,OH)6 octahedra, alternately one and two octahedra wide, extends along [010]. Chains of edge- and corner-shared Mn(O,OH)6 octahedra coupled by PO4 tetrahedra extend along [010]. By sharing octahedron and tetrahedron corners, these two units form a dense three-dimensional framework, which is further strengthened by weak hydrogen bonding. Chemical analyses by electron microprobe gave a unit formula of (Mn4.99Mg0.02)Σ5.01(P1.76Si0.07(As0.07)Σ2.03O8(OH)3.97.

scholarly journals X-Ray Single Crystal Structural Analysis of Magnetically Oriented Microcrystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C1138-C1138
Author(s):  
Chiaki Tsuboi ◽  
Kazuki Aburaya ◽  
Shingo Higuchi ◽  
Fumiko Kimura ◽  
Masataka Maeyama ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Single Crystal ◽  
Three Dimensional ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Data Set ◽  
Uv Curable ◽  
X Ray

We have developed magnetically oriented microcrystal array (MOMA) technique that enables single crystal X-ray diffraction analyses from microcrystalline powder. In this method, microcrystals suspended in a UV-curable monomer matrix are there-dimensionally aligned by special rotating magnetic field, followed by consolidation of the matrix by photopolymerization. From thus achieved MOMAs, we have been succeeded in crystal structure analysis for some substances [1, 2]. Though MOMA method is an effective technique, it has some problems as follows: in a MOMA, the alignment is deteriorated during the consolidation process. In addition, the sample microcrystals cannot be recovered from a MOMA. To overcome these problems, we performed an in-situ X-ray diffraction measurement using a three-dimensional magnetically oriented microcrystal suspension (3D MOMS) of L-alanine. An experimental setting of the in-situ X-ray measurement of MOMS is schematically shown in the figure. L-alanine microcrystal suspension was poured into a glass capillary and placed on the rotating unit equipped with a pair of neodymium magnets. Rotating X-ray chopper with 10°-slits was placed between the collimator and the suspension. By using this chopper, it was possible to expose the X-ray only when the rotating MOMS makes a specific direction with respect to the impinging X-ray. This has the same effect as the omega oscillation in conventional single crystal measurement. A total of 22 XRD images of 10° increments from 0° to 220° were obtained. The data set was processed by using conventional software to obtain three-dimensional molecular structure of L-alanine. The structure is in good agreement with that reported for the single crystal. R1 and wR2 were 6.53 and 17.4 %, respectively. RMSD value between the determined molecular structure and the reported one was 0.0045 Å. From this result, we conclude that this method can be effective and practical to be used widely for crystal structure analyses.

The crystal structure of gersdorffite (III), a distorted and disordered pyrite structure

1968 ◽  
Vol 36 (283) ◽  
pp. 940-947 ◽  
Author(s):  
P. Bayliss ◽  
N. C. Stephenson
Keyword(s):  
Crystal Structure ◽  
Metal Atom ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Partially Ordered ◽  
The Ideal

SummaryThe crystal structure of gersdorffite (III) has been examined with three-dimensional Weissenberg X-ray diffraction data. The unit cell is isometric with a 5·6849 ± 0·0003 Å, space group PI, and four formula units per cell. This structure has the sulphur and arsenic atoms equally distributed over the non-metal atom sites of pyrite. All atoms show significant random displacements from the ideal pyrite positions to produce triclinic symmetry, which serves to distinguish this mineral from a disordered cubic gersdorffite (II) and a partially ordered cubic gersdorffite (I). Factors responsible for the atomic distortions are discussed.

Somersetite, Pb8O(OH)4(CO3)5, a new complex hydrocerussite-related mineral from the Mendip Hills, England

2018 ◽  
Vol 82 (5) ◽  
pp. 1211-1224 ◽  
Author(s):  
Oleg I. Siidra ◽  
Diana O. Nekrasova ◽  
Rick Turner ◽  
Anatoly N. Zaitsev ◽  
Nikita V. Chukanov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Infrared Spectrum ◽  
Weak Interactions ◽  
New Mineral ◽  
Single Crystal Xrd ◽  
X Ray Diffraction ◽  
Electron Pairs ◽  
Xrd Pattern ◽  
X Ray ◽  
Simplified Formula

ABSTRACTThe new mineral somersetite, has been found at Torr Works (‘Merehead quarry’) in Somerset, England, United Kingdom. Somersetite is green or white (typically it is similar visually to hydrocerussite-like minerals but with a mint-green tint), forms plates and subhedral grains up to 5 mm across and up to 2 mm thick. In bi-coloured crystals it forms very thin intergrowths with plumbonacrite. The empirical formula of somersetite is Pb8.00C5.00H4.00O20. The simplified formula is Pb8O(OH)4(CO3)5, which requires: PbO = 87.46, CO2 = 10.78, H2O = 1.76, total 100.00 wt.%.The infrared spectrum of somersetite is similar to that of plumbonacrite and, to a lesser degree, hydrocerussite. Somersetite is hexagonal, P63/mmc, a = 5.2427(7), c = 40.624(6) Å, V = 967.0(3) Å3 and Z = 2. The eight strongest reflections of the powder X-ray diffraction (XRD) pattern [d,Å(I)(hkl)] are: 4.308(33)(103), 4.148(25)(104), 3.581(40)(107), 3.390(100)(108), 3.206(55)(109), 2.625(78)(110), 2.544(98)(0.0.16) and 2.119(27)(1.0.17). The crystal structure was solved from single-crystal XRD data giving R1 = 0.031. The structure of somersetite is unique and consists of the alternation of the electroneutral plumbonacrite-type [Pb5O(OH)2(CO3)3]0 and hydrocerussite-type [Pb3(OH)2(CO3)2]0 blocks separated by stereochemically active lone electron pairs on Pb2+. There are two blocks of each type per unit cell in the structure, which corresponds to the formula [Pb5O(OH)2(CO3)3][Pb3(OH)2(CO3)2] or Pb8O(OH)4(CO3)5 in a simplified representation. The 2D blocks are held together by weak Pb–O bonds and weak interactions between lone pairs.

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