Cadmium complexes of thiones. Part II.1 A synthetic, solution, and solid-state MAS 111/113Cd NMR study of cadmium complexes of 1,3-thiazolidine-2-thione, and the structures of [tetrakis(1,3-thiazolidine-2-thione)cadmium] trifluoromethanesulfonate ([Cd(C3H5NS2)4](CF3SO3)2) and [tetrakis(1,3-thiazolidine-2-thione)cadmium][tetrakis(nitrato-O,O')cadmate] ([Cd(C3H5NS2)4][Cd(O2NO)4])

2001 ◽  
Vol 79 (9) ◽  
pp. 1330-1337
Author(s):  
Umarani Rajalingam ◽  
Philip AW Dean ◽  
Hilary A Jenkins ◽  
Michael Jennings ◽  
James M Hook
Keyword(s):  
Point Group ◽  
Mas Nmr ◽  
Unit Cell ◽  
Group Symmetry ◽  
Cadmium Complexes ◽  
Space Group ◽  
X Ray ◽  
Nmr Data ◽  
Group I ◽  
Cp Mas Nmr

Treatment of Cd(O3SCF3)2 with the stoichiometric quantity of 1,3-thiazolidine-2-thione (tztH) allows isolation of [Cd(tztH)4](O3SCF3)2 (1). When tztH:Cd [Formula: see text] 2 the reaction of Cd(NO3)2·4H2O with tztH leads to [Cd(tztH)4][Cd(O2NO)4] (2). The structures of both 1 and 2 have been determined by single crystal X-ray analysis. Colourless crystals of 1 are orthorhombic, space group Fdd2, with eight molecules per unit cell (Z = 8) of dimensions a = 20.139(3), b = 23.332(5), c = 14.214(3) Å. Those of 2 are tetragonal, space group I [Formula: see text], with four molecules per unit cell (Z = 4) of dimensions a = 13.8853(11), c = 8.077(2) Å. The discrete homoleptic cation [Cd(tztH)4]2+ is characterized for the first time in 1 and 2. The cations are of point group symmetry C2 and S4 in 1 and 2, respectively. In both cases the ligands are S-bound, and the CdS4 kernel is a squashed tetrahedron. In 2, the eight-coordinate anion [Cd(O2NO)4]2- is characterized for the second time. 113Cd CP MAS NMR data are reported for solid 1 and 2, and also for solids produced by fusing Cd(NO3)2·4H2O with different molar ratios amounts of tztH, and by fusing Cd(O3SCF3)2 with six mol equivalents of tztH. In the Cd(NO3)2·4H2O:tztH mixtures, species identified include unreacted cadmium salt 2 ([Cd(tztH)4](NO3)2) and possibly Cd(tztH)3(NO3)2. [Cd(tztH)4](NO3)2 becomes the major species only when a significant excess of tztH is used. In the mixtures with tztH:Cd > 4, neither Cd(NO3)2·4H2O nor Cd(O3SCF3)2 form complexes containing more than four tztH ligands. Reduced-temperature 111Cd NMR data are reported for Cd(ClO4)2·6H2O:tztH mixtures in MeOH. Species identified are Cd(tztH)w2+(solv) (w = 0–3).Key words: 1,3-thiazolidine-2-thione, cadmium complexes, X-ray analysis, 113Cd CP MAS NMR, solution 111Cd NMR, tetrakis(1,3-thiazolidine-2-thione)cadmium(2+) cation, tetrakis(nitrato-O,O')cadmate(2–) anion.

scholarly journals New data on gersdorffite and associated minerals from the Peloritani Mountains (Sicily, Italy)

2021 ◽  
Vol 33 (6) ◽  
pp. 717-726
Author(s):  
Daniela Mauro ◽  
Cristian Biagioni ◽  
Federica Zaccarini
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Quartz Veins ◽  
Group I

Abstract. Gersdorffite, ideally NiAsS, and associated minerals from Contrada Zillì (Peloritani Mountains, Sicily, Italy) have been characterized through electron microprobe analysis and X-ray diffraction. Primary minerals, hosted in quartz veins, are represented by gersdorffite, tetrahedrite-(Fe), and chalcopyrite with minor pyrite and galena. Rare aikinite inclusions were observed in tetrahedrite-(Fe) and chalcopyrite. Gersdorffite occurs as euhedral to subhedral crystals, up to 1 mm in size, with (Sb,Bi)-enriched cores and (Fe,As)-enriched rims. Its chemical composition is (Ni0.79−0.95Fe0.18−0.04Co0.04−0.01)(As0.90−1.03Sb0.10−0.00Bi0.02−0.00)S0.98−0.92. It crystallizes in the space group P213, with unit-cell parameters a=5.6968(7) Å, V=184.88(7) Å3, and Z=4, and its crystal structure was refined down to R1= 0.035. Associated tetrahedrite-(Fe) has chemical formula (Cu5.79Ag0.07)Σ5.86(Cu3.96Fe1.59Zn0.45)Σ6.00(Sb3.95As0.17Bi0.03)Σ4.15S13.06, with unit-cell parameters a= 10.3815(10) Å, V=1118.9(3) Å3, and space group I-43m. Its crystal structure was refined to R1=0.027. Textural and crystallographic data suggest a polyphasic crystallization of gersdorffite under low-temperature conditions.

Octahedral tilting in the tungsten bronzes

2015 ◽  
Vol 71 (3) ◽  
pp. 342-348 ◽  
Author(s):  
Thomas A. Whittle ◽  
Siegbert Schmid ◽  
Christopher J. Howard
Keyword(s):  
Group Theory ◽  
Computer Program ◽  
Unit Cell ◽  
Group Symmetry ◽  
Space Group Symmetry ◽  
Space Group ◽  
X Ray ◽  
Unit Cells ◽  
Octahedral Tilting ◽  
Special Points

Possibilities for `simple' octahedral tilting in the hexagonal and tetragonal tungsten bronzes (HTB and TTB) have been examined, making use of group theory as implemented in the computer programISOTROPY. For HTB, there is one obvious tilting pattern, leading to a structure in space groupP63/mmc. This differs from the space groupP63/mcmfrequently quoted from X-ray studies – these studies have in effect detected only displacements of the W cations from the centres of the WO6octahedra. The correct space group, taking account of both W ion displacement and the octahedral tilting, isP6322 – structures in this space group and matching this description have been reported. A second acceptable tilting pattern has been found, leading to a structure inP6/mmmbut on a larger `2 × 2 × 2' unit cell – however, no observations of this structure have been reported. For TTB, a search at the special points of the Brillouin zones revealed only one comparable tilting pattern, in a structure with space-group symmetryI4/mon a `21/2 × 21/2by 2' unit cell. Given several literature reports of larger unit cells for TTB, we conducted a limited search along the lines of symmetry and found structures with acceptable tilt patterns inBbmmon a `21/22 × 21/2 × 2' unit cell. A non-centrosymmetric version has been reported in niobates, inBbm2 on the same unit cell.

scholarly journals Symmetry-extended counting rules for periodic frameworks

2014 ◽  
Vol 372 (2008) ◽  
pp. 20120029 ◽  
Author(s):  
S. D. Guest ◽  
P. W. Fowler
Keyword(s):  
Point Group ◽  
Factor Group ◽  
Unit Cell ◽  
Group Symmetry ◽  
Point Group Symmetry ◽  
Space Group ◽  
Counting Rules ◽  
Periodic Frameworks ◽  
Explicit Expressions

A symmetry-adapted version of the Maxwell rule appropriate to periodic bar-and-joint frameworks is obtained, and is further extended to body-and-joint systems. The treatment deals with bodies and forces that are replicated in every unit cell, and uses the point group isomorphic to the factor group of the space group of the framework. Explicit expressions are found for the numbers and symmetries of detectable mechanisms and states of self-stress in terms of the numbers and symmetries of framework components. This approach allows detection and characterization of mechanisms and states of self-stress in microscopic and macroscopic materials and meta-materials. Illustrative examples are described. The notion of local isostaticity of periodic frameworks is extended to include point-group symmetry.

Processing and Properties of Plate 3D Braided Material Based on Space Group P¯3 Symmetry

2012 ◽  
Vol 161 ◽  
pp. 250-254 ◽  
Author(s):  
Wen Suo Ma ◽  
Chuang Xu ◽  
Kai Li ◽  
Ling Ling Zhang
Keyword(s):  
Mathematical Model ◽  
Point Group ◽  
Unit Cell ◽  
Fiber Volume ◽  
Volume Percentage ◽  
Space Group ◽  
Geometry Structure ◽  
Group I ◽  
Symmetry Operations ◽  
Variation Tendency

A novel geometry structure of unit cell was deduced by using the point group S6 corresponding to symmetry operations. Based on the symmetry of space group P3, a new 3D braided material was obtained by transforming the new unit cell symmetrically. The plate processing corresponding to this geometry structure was studied. The fiber volume percentage and its variation tendency of the 3D braided material were predicted through establishing mathematical model.

Purification, crystallization and preliminary X-ray analysis of catabolic ornithine carbamoyltransferase from Pseudomonas aeruginosa

1999 ◽  
Vol 55 (9) ◽  
pp. 1591-1593 ◽  
Author(s):  
G. Sainz ◽  
J. Vicat ◽  
R. Kahn ◽  
C. Tricot ◽  
V. Stalon ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Point Group ◽  
Unit Cell ◽  
Group Symmetry ◽  
Ornithine Carbamoyltransferase ◽  
Unit Cell Parameters ◽  
Crystal Forms ◽  
Space Group ◽  
Cell Parameters ◽  
Hexagonal Crystals

The catabolic ornithine carbamoyltransferase (OTCase) from Pseudomonas aeruginosa exhibits allosteric behaviour, with two conformational states of the molecule: an active R form and an inactive T form. The enzyme is a dodecamer with a molecular mass of 455700 Da. Three crystal forms have been obtained. Crystals of allosteric state T are rhombohedral, belonging to the R3 space group, with hexagonal unit-cell parameters a = b = 180.6, c = 122.0 Å. They diffract to a resolution of 4.5 Å. Two crystal forms for allosteric state R have been obtained, with hexagonal and cubic symmetries. Hexagonal crystals, which diffract to a resolution of 3.4 Å, belong to the space group P63 with unit-cell parameters a = b = 140.8, c = 145.6 Å. The cubic crystals belong to space group I23, with unit-cell parameter a = 134.32 Å and diffract to a resolution better than 2.5 Å. In all crystal forms, the dodecamer exhibits a 23 point-group symmetry.

scholarly journals Beiträge zur Chemie des Bors, 153 [1] Die Kristall- und Molekülstruktur eines 1.3.2-Dioxaborolan-2-yl-1.3.2-dioxaborolans

1984 ◽  
Vol 39 (11) ◽  
pp. 1463-1466 ◽  
Author(s):  
H. Nöth
Keyword(s):  
Point Group ◽  
Group Symmetry ◽  
Monoclinic Space Group ◽  
Point Group Symmetry ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography

Abstract The structure of the title com pound 5 has been investigated by X-ray crystallography in order to discern between two structural alternatives. 5 crystallizes in the monoclinic space group P21/c, and almost planar B-B bonded dioxaborolane rings are present in the molecule. 5 possesses a crystallographically imposed center of inversion, and approaches the point group symmetry D2h-

X-ray structures of triphenylphosphine and 1,2,5-triphenylphosphole products with dimethyl acetylenedicarboxylate tetramer

1994 ◽  
Vol 72 (12) ◽  
pp. 2428-2442 ◽  
Author(s):  
Martin B. Hocking ◽  
Frances W. van der Voort Maarschalk
Keyword(s):  
Triphenylphosphine Oxide ◽  
Previous Method ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Dimethyl Acetylenedicarboxylate ◽  
Polymeric Product ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Nmr Data

A tetramer of dimethyl acetylenedicarboxylate, tetramethyl 4-methoxy-5-[1,2,3-tris(methoxycarbonyl)-2-cyclopropen-1-yl]-7-oxabicyclo[2.2.1]hepta-2,5-diene-1,2,3,6-tetracarboxylate 3, was recovered from old stocks of the monomer, and was also prepared thermally from the monomer by a variation of a previous method. NMR data and an X-ray crystal structure were determined for a red 1:1 adduct of this ester with triphenylphosphine. This red adduct, tetramethyl 4-methoxy-5-[1,2,3-tris(carbomethoxy)-3-triphenylphosphoranylidenepropen-1-yl]-7-oxabicyclo[2.2.1]hepta-2,5-diene-1,2,3,6-tetracarboxylate 5, crystallized in the triclinic space group P1 (No. 2) with two molecules in the unit cell (a = 12.315(2) Å, b = 12.321(2) Å, c = 14.652(2) Å, α = 110.60(1)°, β = 90.62 (1)°, and γ = 103.22(1)°). Refinement converged at R = 0.0694 (Rw = 0.0986) for 542 parameters using 4714 reflections with I > 2σ(I). Triphenylphosphine oxide did not react with tetramer 3. Reaction of the tetramer of dimethyl acetylenedicarboxylate 3 with 1,2,5-triphenylphosphole gave an orange product with concomitant loss of a furan triester. NMR data confirmed that this was not a simple adduct, and examination of a crystal by X-ray established the structure as the dichloromethane complex of tetramethyl 1,9,10-triphenyl-1-phospha(V)tricyclo[5,2,1,05,10] deca-1,3,5,8-tetraene-2,3,4,6-tetracarboxylate 10. This orange product crystallized in the monoclinic space group P21/c (No. 14) with four molecules in the unit cell (a = 10.056(2) Å, b = 14.280(1) Å, c = 23.892(3) Å, α = 90.0°, β = 94.15(1)°, and γ = 90.0°). Refinement converged at R = 0.0683 (Rw = 0.0710) for 540 parameters using 3180 independent reflections with I > 3σ(I). The tetramer 3 did not react with 1,2,5-triphenylphosphole-1-oxide quickly, but after 9 months gave a white, probably polymeric, product.

Die Kristallstrukturen von cis- und trans-Dichlorstilben

1984 ◽  
Vol 39 (4) ◽  
pp. 409-415 ◽  
Author(s):  
Evamarie Hey ◽  
Frank Weller ◽  
Kurt Dehnicke ◽  
Günther Maier
Keyword(s):  
Bond Length ◽  
Point Group ◽  
Unit Cell ◽  
Dihedral Angles ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Phenyl Rings ◽  
Cis And Trans

The crystal structures of cis- and trans-dichlorostilbene were determined from X-ray diffraction data, cw-dichlorostilbene crystallizes in the rhombohedral space group R3̄ with 18 formula units per unit cell (821 observed independent reflexions, R = 0.064) with the dimensions a = b = 3323, c = 601 pm, γ = 120°. The molecule corresponds to the point group C1 with a C = C bond length of 133 pm; the dihedral angles of the phenyl rings with the corresponding C = C-Cl plane are 48° and 72°, respectively. Trans-dichlorostilbene crystallizes in the monoclinic space group P21/n with two formula units per unit cell (1138 independent reflexions, R = 0.056) with the dimensions a = 572, b = 1733, c = 641 pm, β = 111°. The molecule is centrosymmetric (Ci) with a C = C bond length of 133 pm; the dihedral angle of the phenyl rings and the Cl - C = C plane is 71°. The stilbene molecules are disordered about the centre of symmetry in two orientations with the ratio 3:7.

Darstellung, Eigenschaften und Struktur des Cyclopentadienyl(1.3-diborolenyl)nickel-Sandwiehs [1] / Synthesis, Properties and Structure of the Cyclopentadienyl(1,3-diborolenyl)nickel Sandwich [1]

1978 ◽  
Vol 33 (12) ◽  
pp. 1410-1416 ◽  
Author(s):  
Walter Siebert ◽  
Manfred Bochmann ◽  
Joseph Edwin ◽  
Carl Krüger ◽  
Yi-Hung Tsay
Keyword(s):  
Structure Analysis ◽  
Title Compound ◽  
Sandwich Structure ◽  
Unit Cell ◽  
Space Group ◽  
X Ray ◽  
Nmr Data ◽  
Synthesis Properties

Abstract 1,3,4,5-Tetraethyl-2-methyl-1,3-diborolene (5) reacts with nickelocene and dimeric cyclopentadienylcarbonylnickel, yielding orange red 4 a, a diamagnetic nickelocene analogue. 1H and 11B NMR data indicate a sandwich structure, which is confirmed by X-ray structure analysis. The title compound crystallizes in the space group Pnma with a = 9.265(I), b = 15.1343(9), c = 12.777(2) Å and four molecules in the unit cell. All metal carbon distances are similar to those of the isoelectronic ferrocene.

scholarly journals An X-ray study of horse methaemoglobin. I

1947 ◽  
Vol 191 (1024) ◽  
pp. 83-132 ◽  
Keyword(s):  
Internal Structure ◽  
Free Water ◽  
Unit Cell ◽  
Group Symmetry ◽  
Monoclinic Space Group ◽  
Average Height ◽  
X Ray Diffraction ◽  
Molecular Scattering ◽  
Space Group ◽  
X Ray

The paper describes a detailed study of horse methaemoglobin by single crystal X-ray diffraction methods. The results give information on the arrangement of the molecules in the crystal, their shape and dimensions, and certain features of their internal structure. Horse methaemoglobin crystallizes in the monoclinic space group C 2 with two molecules of weight 66, 700 per unit cell. In addition, the wet crystals contain liquid of crystallization which fills 52.4% of the unit cell volume. Deliberate variations in the amount and com­position of the liquid of crystallization, and the study of the effects of such variations on the X-ray diffraction pattern, form the basis of the entire analysis. The composition of the liquid of crystallization can be varied by allowing heavy ions to diffuse into the crystals. This increases the scattering contribution of the liquid relative to that of the protein molecules and renders it possible to distinguish the one from the other. The method is analogous to that of isomorphous replacement commonly used in X-ray analysis. It yielded valuable information on the shape and character of the haemoglobin molecules and also led to the determination of the phase angles of certain reflexions. The amount of liquid of crystallization was varied by swelling and shrinkage of the crystals. This involves stepwise, reversible transitions between different well-defined lattices, each being stable in a particular environment of the crystal. The lattice changes were utilized in two different ways: the first involved comparison of Patters on projections at different stages of swelling and shrinkage, and the second an attempt to trace the molecular scattering curve as a function of the diffraction angle. The results of the analysis can be summarized as follows. The methaemoglobin molecules resemble cylinders of an average height of 34 A and a diameter of 57 A. In the crystal these cylinders form close-packed layers which alternate with layers of liquid of crystallization. The layers of haemoglobin molecules themselves do not swell or shrink, either in thickness or in area, except on complete drying, and lattice changes merely involve a shearing of the haemoglobin layers relative to each other, combined with changes in the thickness of the liquid layer. Thus the molecules do not seem to be penetrated by the liquid of crystallization, and their structure is unaffected by swelling and shrinkage of the crystal. Space-group symmetry requires that each molecule consists of two chemically and struc­turally identical halves. Evidence concerning the internal structure of the molecules comes both from two-dimensional Patterson projections and one-dimensional Fourier projections. The former indicate that interatomic vectors of 9 to 11 A occur frequently in many directions, and the latter show four prominent concentrations of scattering matter just under 9 A apart along a line normal to the layers of haemoglobin molecules. No structural interpretation of these features is as yet attempted. The liquid of crystallization consists of two distinct components: water ‘bound’ to the protein and not available as solvent to diffusing ions, and ‘free’ water in dynamic equilibrium with the suspension medium. An estimate of the ‘frictional ratio’ based on the molecular shape and hydration found in this analysis is in good agreement with the frictional ratio calculated from the sedimentation constant.

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