scholarly journals Comparison of the crystal structures of the low- and high-temperature forms of bis[4-(dimethylamino)pyridine]dithiocyanatocobalt(II)

2021 ◽  
Vol 77 (11) ◽  
Author(s):  
Christoph Krebs ◽  
Inke Jess ◽  
Christian Näther
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Low Temperature ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Three Dimensional ◽  
Monoclinic Space Group ◽  
Temperature Form ◽  
Dimensional Network ◽  
High Temperature Form

Single crystals of the high-temperature form I of [Co(NCS)2(DMAP)2] (DMAP = 4-dimethylaminopyridine, C7H10N2) were obtained accidentally by the reaction of Co(NCS)2 with DMAP at slightly elevated temperatures under kinetic control. This modification crystallizes in the monoclinic space group P21/m and is isotypic with the corresponding Zn compound. The asymmetric unit consists of one crystallographically independent Co cation and two crystallographically independent thiocyanate anions that are located on a crystallographic mirror plane and one DMAP ligand (general position). In its crystal structure the discrete complexes are linked by C—H...S hydrogen bonds into a three-dimensional network. For comparison, the crystal structure of the known low-temperature form II, which is already thermodynamically stable at room temperature, was redetermined at the same temperature. In this polymorph the complexes are connected by C—H...S and C—H...N hydrogen bonds into a three-dimensional network. At 100 K the density of the high-temperature form I (ρ = 1.457 g cm−3) is lower than that of the low-temperature form II (ρ = 1.462 g cm−3), which is in contrast to the values determined by XRPD at room temperature. Therefore, these two forms represent an exception to the Kitaigorodskii density rule, for which extensive intermolecular hydrogen bonding in form II might be responsible.

Synthese und Kristallstrukturen von N-[ω-(Dimethylammonio)alkyl]- N´,N´,N´´,N´´-tetramethylguanidinium-chlorid-tetraphenylboraten / Synthesis and Crystal Structures of N-[ω-(Dimethylammonio)alkyl]-N´,N´,N´´,N´´- tetramethylguanidinium Chloride Tetraphenylborates

2010 ◽  
Vol 65 (7) ◽  
pp. 907-916 ◽  
Author(s):  
Ioannis Tiritiris ◽  
Falk Lissner ◽  
Thomas Schleid ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Room Temperature ◽  
Chloride Ions ◽  
Monoclinic Space Group ◽  
Temperature Structure ◽  
Space Group ◽  
Temperature Modification

Dicationic N,N´,N´,N´´,N´´-pentasubstituted guanidinium dichlorides 4a, b are obtained from the chloroformamidinium salt 2 and diamines 3a, b. N-[2-(Dimethylammonio)ethyl]-N´,N´,N´´,N´´-tetramethylguanidinium chloride tetraphenylborate (5a) and N-[3-(dimethylammonio)propyl]-N´,N´,N´´,N´´-tetramethylguanidinium chloride tetraphenylborate (5b) were synthesized from 4a, b by anion metathesis with one equivalent of sodium tetraphenylborate. The thermal properties of the salts 5a, b were studied by means of DSC methods, and their crystal structures were determined by single-crystal X-ray diffraction analysis. For 5a a solid-solid phase transition is observed at −156 ◦C to a low-temperature structure. The room-temperature modification (α-5a) crystallizes in the centrosymmetric orthorhombic space group Pbca (a = 13.1844(4), b = 13.8007(4), c = 34.7537(11) A° ).The guanidinium ions are interconnected via chloride ions through bridging N-H· · ·Cl hydrogen bonds, providing isolated units. The tetraphenylborate ions show some dynamic disordering in the crystal structure. The low-temperature modification (β -5a) also crystallizes orthorhombically, but in the non-centrosymmetric space group Pna21 (a = 13.1099(4), b = 69.1810(11), c = 13.5847(5) A° ) and consists of four crystallographically independent cations and anions in the unit cell. Compared with the room-temperature structure, a similar N-H· · ·Cl hydrogen bond pattern is observed in the β -phase, but the tetraphenylborate ions are now completely ordered. 5b crystallizes in the monoclinic space group P21/c (a = 10.8010(3), b = 14.1502(5), c = 20.9867(9) A° , β = 94.322(1)◦). In the crystal structure the guanidinium ions are linked via chloride ions through N-H· · ·Cl hydrogen bonds, but in contrast to 5a two infinite strands are formed along the a axis with the tetraphenylborate ions interspersed between them for charge compensation.

scholarly journals Synthesis, Crystal structure of hepta (pyridinium) bis (hexachlorobismuthate (III)) nitrate [C5H6N]7(BiCl6)2(NO3)

2013 ◽  
Vol 9 (2) ◽  
pp. 1975-1987
Author(s):  
Ben Tahar Fayçal ◽  
Perez Olivier ◽  
Slaheddine Chaabouni
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Room Temperature ◽  
Three Dimensional ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
Cell Parameters ◽  
Dimensional Network

An hepta (pyridinium) bis (hexachlorobismuthate (III)) nitrate, (C5H6N)7(BiCl6)2(NO3) crystallizes at room temperature in the monoclinic system, space group P21/n, with the following unit-cell parameters: a = 9.555(1) Å, b = 16.847(1) Å, c = 32.522(1) Å, β = 94.37° , V = 5219.8 Å3 and four molecules per unit cell. Its crystal structure was determined and refined down to R1 = 0.0504, wR2 = 0.0667. The structure of the title compound, (C5H6N)7(BiCl6)2(NO3) consists of seven monoprotonated pyridinium (C5H6N)+ cations, two independent octahedron [BiCl6]3- and an isolated NO3- anion. These entities are linked together through N-H.....Cl and N-H.....O hydrogen bonds, originating from the (C5H6N)+ groups and the isolated anion of nitrate to forming a three dimensional network.

scholarly journals 4-(3-Chlorophenyl)-1-(3-chloropropyl)piperazin-1-ium chloride redetermined at 100 K

IUCrData ◽  
2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Muzzaffar Ahmad Bhat ◽  
Sanjay K. Srivastava ◽  
Pooja Sharma ◽  
Ambika Chopra ◽  
Ray J. Butcher
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Ion Pairs ◽  
Three Dimensional ◽  
Chair Conformation ◽  
Temperature Data ◽  
Acta Cryst ◽  
Piperazine Ring ◽  
Dimensional Network

The crystal structure of the title salt, C13H19Cl2N2+·Cl−, has been reported previously [Homrighausen & Krause Bauer (2002).Acta Cryst.E58, o1395–o1396] based on room-temperature data, where it was found to contain a disordered chloropropyl group. We now present the structure at 100 K in which the chloropropyl group is ordered. The piperazine ring adopts a chair conformation with the exocyclic N—C bonds in equatorial orientations. The dihedral angle between the piperazine ring (all atoms) and the benzene ring is 28.47 (5)°. The chloropropyl group has an extended conformation [N—C—C—C = −177.25 (8) ° and C—C—C—Cl = 174.23 (7)°]. In the crystal, charge-assisted N—H...Cl hydrogen bonds link the cation and anion into ion pairs. Numerous weak C—H...Cl interactions link the ion pairs into a three-dimensional network. Short Cl...Cl contacts [3.2419 (4) Å] are also observed.

Structural Studies of GeTe-AgSbTe2 Alloys

2007 ◽  
Vol 1044 ◽  
Author(s):  
Alan Thompson ◽  
Jeff Sharp ◽  
C.J Rawn ◽  
B.C. Chackoumakos
Keyword(s):  
Crystal Structure ◽  
Phase Transformation ◽  
High Temperature ◽  
Low Temperature ◽  
Systematic Study ◽  
Structural Studies ◽  
Temperature Form ◽  
P Type ◽  
High Temperature Form ◽  
Important Constituent

AbstractGeTe, a small bandgap semiconductor that has native p-type defects due to Ge vacancies, is an important constituent in the thermoelectric material known as “TAGS” [1]. TAGS is an acronym for alloys of GeTe with AgSbTe2, and compositions are normally designated as TAGS-x, where x is the fraction of GeTe. TAGS-85 is the most important with regard to applications, and there also is commercial interest in TAGS-80. The crystal structure of GeTe1+δ has a composition-dependent phase transformation at a temperature ranging from 430°C (δ = 0) to ∼ 400°C (δ = 0.02) [2]. The high temperature form is cubic. The low temperature form is rhombohedral for δ < 0.01, as is the case for good thermoelectric performance. Addition of AgSbTe2 shifts the phase transformation to lower temperatures, and one of the goals of this work is a systematic study of the dependence of transformation temperature on the parameter x. We present results on phase transformations and associated instabilities in TAGS compositions in the range of 70-85 at.% GeTe.

Crystal Structure of Diethylammonium p-Aminobenzoate (Nevanide)

1999 ◽  
Vol 52 (6) ◽  
pp. 625 ◽  
Author(s):  
Graham Smith ◽  
Colin H. L. Kennard ◽  
Karl A. Byriel
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Ion Pairs ◽  
Three Dimensional ◽  
The Other ◽  
Monoclinic Space Group ◽  
Dimensional Network ◽  
A Cell ◽  
Amine Groups

The crystal structure of Nevanide (diethylammonium p-aminobenzoate) has been determined and refined to a residual R 0·055 for 2797 observed reflections. Crystals are monoclinic, space group C 2/c, with 32 ion pairs in a cell with dimensions a 29·510(6), b 17·150(1), c 20·473(5) Å, β 115·153(9)°. The structure is made up of a network of hydrogen-bonded ions; in this network the 4-aminobenzoate anions form a primary cyclic tetramer unit in which the amine groups of two residues are linked tail to tail through hydrogen bonds to single carboxylate oxygens of the other two residues. All oxygens are then linked peripherally to layers of diethylammonium cations by strong hydrogen bonding, with all possible hydrogen bonding sites utilized, giving a three-dimensional network array.

scholarly journals 1,3,4-Tri-O-acetyl-2-N-(trifluoroacetyl)-β-L-fucose

2014 ◽  
Vol 70 (2) ◽  
pp. o134-o135
Author(s):  
David C. McCutcheon ◽  
Peter Norris ◽  
Matthias Zeller
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Three Dimensional ◽  
Chair Conformation ◽  
X Ray ◽  
Compound C ◽  
Product Mixture ◽  
Dimensional Network ◽  
Graph Set

The title compound, C14H18F3NO8, was produced through conjugation of 1,3,4-tri-O-acetyl-2-azidodeoxy-α,β-L-fucose with trifluoroacetyl chloride in the presence of bis(diphenylphosphino)ethane in tetrahydrofuran at room temperature. The X-ray crystal structure reveals that the β-anomer of the product mixture crystallizes from ethyl acetate/hexanes. The compound exists in a typical chair conformation with the maximum possible number of substituents, four out of five, located in the sterically preferred equatorial positions. The major directional force facilitating packing of the molecules are N—H...O hydrogen bonds involving the amide moieties of neighboring molecules, which connect molecules stacked along thea-axis direction into infinite strands with aC11(4) graph-set motif. Formation of the strands is assisted by a number of weaker C—H...O interactions involving the methine and methyl H atoms. These strands are connected through further C—H...O and C—H...F interactions into a three dimensional network

Two reversible enantiotropic phase transitions in a pentacoordinate silicon complex with anO,N,O′-tridentate valinate ligand

2015 ◽  
Vol 71 (6) ◽  
pp. 511-516 ◽  
Author(s):  
Anke Schwarzer ◽  
Sabine Fels ◽  
Uwe Böhme
Keyword(s):  
Phase Transitions ◽  
High Temperature ◽  
Low Temperature ◽  
Monoclinic Space Group ◽  
Isopropyl Group ◽  
Orthorhombic Space Group ◽  
Chiral Compound ◽  
Space Group ◽  
Temperature Form ◽  
High Temperature Form

Dimethyl[N-(4-oxidopent-3-en-2-ylidene)valinato-κ3O,N,O′]silicon(IV), C12H21NO3Si, (II), crystallizes in the orthorhombic space groupP212121. The chiral compound undergoes two sharp enantiotropic phase transitions upon cooling. The first transformation occurs at 163 K to yield a unit cell with one axis having double length. This intermediate-temperature form has the monoclinic space groupP21. The second transition takes place at 142 K and converts the single crystal into the low-temperature form in the orthorhombic space groupP212121. This transition proceeds under tripling of theaaxis of the high-temperature form. Both phase transitions are fully reversible and correspond to order–disorder transitions of the isopropyl group of the valine unit in the ligand backbone. The phase transitions presented here raise questions, since they do not fit into the rules of group–subgroup relationships.

2-Ethyl-6-methylpyridin-3-ol and its salt bis(2-ethyl-3-hydroxy-6-methylpyridinium) succinate

2012 ◽  
Vol 68 (9) ◽  
pp. o365-o368 ◽  
Author(s):  
Alexander S. Lyakhov ◽  
Ludmila S. Ivashkevich ◽  
Vladimir L. Survilo ◽  
Alexander M. Kipnis ◽  
Tatjana V. Trukhachova
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Hydroxy Group ◽  
Pyridine Ring ◽  
Three Dimensional ◽  
Monoclinic Space Group ◽  
Π Interactions ◽  
Carboxylate Groups ◽  
Dimensional Network ◽  
Polymeric Chains

The title compounds, C8H11NO, (I), and 2C8H12NO+·C4H4O42−, (II), both crystallize in the monoclinic space groupP21/c. In the crystal structure of (I), intermolecular O—H...N hydrogen bonds combine the molecules into polymeric chains extending along thecaxis. The chains are linked by C—H...π interactions between the methylene H atoms and the pyridine rings into polymeric layers parallel to theacplane. In the crystal structure of (II), the succinate anion lies on an inversion centre. Its carboxylate groups interact with the 2-ethyl-3-hydroxy-6-methylpyridinium cationsviaintermolecular N—H...O hydrogen bonds with the pyridine ring H atoms and O—H...O hydrogen bonds with the hydroxy H atoms to form polymeric chains, which extend along the [\overline{1}01] direction and compriseR44(18) hydrogen-bonded ring motifs. These chains are linked to form a three-dimensional network through nonclassical C—H...O hydrogen bonds between the pyridine ring H atoms and the hydroxy-group O atoms of neighbouring cations. π–π interactions between the pyridine rings and C—H...π interactions between the methylene H atoms of the succinate anion and the pyridine rings are also present in this network.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

scholarly journals Crystal structure of K[Hg(SCN)3] – a redetermination

2014 ◽  
Vol 70 (9) ◽  
pp. i46-i46 ◽  
Author(s):  
Matthias Weil ◽  
Thomas Häusler
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
Three Dimensional ◽  
Lattice Parameters ◽  
Bond Lengths ◽  
Dimensional Network ◽  
Anisotropic Displacement Parameters ◽  
Precision And Accuracy ◽  
Standard Deviations ◽  
Atomic Coordinates

The crystal structure of the room-temperature modification of K[Hg(SCN)3], potassium trithiocyanatomercurate(II), was redetermined based on modern CCD data. In comparison with the previous report [Zhdanov & Sanadze (1952).Zh. Fiz. Khim.26, 469–478], reliability factors, standard deviations of lattice parameters and atomic coordinates, as well as anisotropic displacement parameters, were revealed for all atoms. The higher precision and accuracy of the model is, for example, reflected by the Hg—S bond lengths of 2.3954 (11), 2.4481 (8) and 2.7653 (6) Å in comparison with values of 2.24, 2.43 and 2.77 Å. All atoms in the crystal structure are located on mirror planes. The Hg2+cation is surrounded by four S atoms in a seesaw shape [S—Hg—S angles range from 94.65 (2) to 154.06 (3)°]. The HgS4polyhedra share a common S atom, building up chains extending parallel to [010]. All S atoms of the resulting1∞[HgS2/1S2/2] chains are also part of SCN−anions that link these chains with the K+cations into a three-dimensional network. The K—N bond lengths of the distorted KN7polyhedra lie between 2.926 (2) and 3.051 (3) Å.

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