scholarly journals Crystal structures and conformers of CyMe4-BTBP

Nukleonika ◽  
2015 ◽  
Vol 60 (4) ◽  
pp. 853-857 ◽  
Author(s):  
Krzysztof Lyczko ◽  
Slawomir Ostrowski
Keyword(s):  
Crystal Structure ◽  
Dft Calculations ◽  
Crystal Structures ◽  
Gas Phase ◽  
Trans Orientation

Abstract The crystal structure of new conformation of the CyMe4-BTBP ligand (ttc) has been presented. The ttt conformer of this compound in a form of THF solvate has been also crystallized. The geometries of six possible conformations (ttt, ttc, tct, tcc, ctc and ccc) of the CyMe4-BTBP ligand have been modeled in the gas phase and in solutions (MeOH and H2O) by DFT calculations using B3LYP/6-31G(d,p) method. According to the calculations, in the three different media the conformers with trans orientation of the N atoms in the bipyridyl moiety are the most stable.

Investigations of the mono- and dicycloaddition reactions of [SNS][MF6] (M = As, Sb) with the dinitriles NCC(O)CN and NCC(Cl)2CN — Energetics and the preference for [SNS]+ dicycloaddition products in solution and solid state

2007 ◽  
Vol 85 (2) ◽  
pp. 96-104 ◽  
Author(s):  
T Stanley Cameron ◽  
Andreas Decken ◽  
Mary Gabriel ◽  
Carsten Knapp ◽  
Jack Passmore
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Dft Calculations ◽  
Crystal Structures ◽  
Gas Phase ◽  
Intermolecular Interactions ◽  
Cycloaddition Reactions ◽  
Solid Phases ◽  
C Nmr

The stepwise symmetry-allowed cycloaddition reactions of [SNS]+ with the dinitriles NC–X–CN (X = CCl2, CO) were investigated. The reaction of [SNS]+ and dinitrile in 2:1 ratio yielded the dicycloaddition product quantitatively after 2 weeks (in situ 13C NMR). At a 1:1 ratio, mixtures of mono- and dicycloaddition products were obtained that could not be completely separated from one another. The energetics of the reaction were estimated in the gas phase, in solution (SO2 and CH2Cl2), and solid phases using DFT calculations (PBE0/6-311G*) and a "volume-based thermodynamics" approach for lattice enthalpies. Monocycloaddition products are stable in the gas phase and in solution with respect to disproportionation reactions, but in the solid state the disproportionation of 2 [NC–X–(CNSNS)][AsF6] into [X(CNSNS)2][AsF6]2 and NC–X–CN is strongly favored because of the higher lattice enthalpy of the 1:2 salt. In the gas phase, the second cycloaddition is endothermic because of the charge repulsion of the two positive charges, but in the solid state the reaction is strongly favored because of the lattice enthalpy gain on the formation of the 1:2 ([X(CNSNS)2][AsF6]2) from two 1:1 salts ([NC–X–(CNSNS)][AsF6] and [SNS][MF6]). The crystal structures of the dicycloaddition products [Cl2C(CNSNS)2][AsF6]2 and [OC(CNSNS)2][AsF6]2 and the monocycloaddition product [Cl2C(CNSNS)CN][AsF6] were obtained. In [Cl2C(CNSNS)CN][AsF6], the free nitrile groups interact with neighboring heterocycles further demonstrating that potential of free nitrile groups for introducing intermolecular interactions. [OC(CNSNS)2]2+ is a planar dication, which adopts the conformation with Sδ+···Oδ– contacts to optimize intramolecular electrostatic interactions.Key words: crystal structure, sulfur-nitrogen, 1,3,2,4-dithiadiazolyium, nitriles, cycloaddition, DFT calculations, thermodynamics, energetics.

Crystal structure, phase transition and properties of indium(iii) sulfide

2020 ◽  
Vol 49 (44) ◽  
pp. 15903-15913
Author(s):  
Paweł Wyżga ◽  
Wilder Carrillo-Cabrera ◽  
Lev Akselrud ◽  
Igor Veremchuk ◽  
Jörg Wagler ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Dft Calculations ◽  
Crystal Structures ◽  
Thermoelectric Properties ◽  
Structural Part ◽  
Β Phase ◽  
Structure Phase ◽  
Structure Phase Transition

This report presents studies of crystal structures of α- and β-In2S3 as well as a mechanism of the 1st order α–β phase transition. The structural part is supported by an analysis of thermoelectric properties and by DFT calculations.

scholarly journals Substituent Effects in 3,3’ Bipyrazole Derivatives. X-ray Crystal Structures, Molecular Properties and DFT Analysis

2021 ◽  
Vol 68 (3) ◽  
pp. 718-727
Author(s):  
Ibrahim Bouabdallah ◽  
Tarik Harit ◽  
Mahmoud Rahal ◽  
Fouad Malek ◽  
Monique Tillard ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Solid State ◽  
Dft Calculations ◽  
Single Crystal ◽  
Crystal Structures ◽  
Density Functional ◽  
Substituent Effects ◽  
Functional Theory ◽  
X Ray

The single crystal X-ray structure of new 1,1’-bis(2-nitrophenyl)-5,5’-diisopropyl-3,3’-bipyrazole, 1, is triclinic P I–, a = 7.7113(8), b = 12.3926(14), c = 12.9886(12) Å, α = 92.008(8), β = 102.251(8), γ = 99.655(9)°. The structural arrangement is compared to that of 5,5’-diisopropyl-3,3’-bipyrazole, 5, whose single crystal structure is found tetragonal I41/a, a = b = 11.684(1), c = 19.158(1) Å. The comparison is also extended to the structures previously determined for 1,1’-bis(2-nitrophenyl)-5,5’-propyl-3,3’-bipyrazole, 2, 1,1’-bis(4-nitrophenyl)-5,5’-diisopropyl-3,3’-bipyrazole, 3, and 1,1’-bis(benzyl)-5,5’-diisopropyl-3,3’-bipyrazole, 4. Density Functional Theory (DFT) calculations are used to investigate the molecular geometries and to determine the global reactivity parameters. The geometry of isolated molecules and the molecular arrangements in the solid state are analyzed according to the nature of the groups connected to the bipyrazole core.

scholarly journals Validation of a search technique for crystal structure prediction of flexible molecules by application to piracetam

2005 ◽  
Vol 61 (5) ◽  
pp. 558-568 ◽  
Author(s):  
Harriott Nowell ◽  
Sarah L. Price
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Crystal Structures ◽  
Gas Phase ◽  
Intermolecular Interactions ◽  
Structure Prediction ◽  
Low Energy ◽  
Crystal Structure Prediction ◽  
New Approach ◽  
Flexible Molecules

A new approach to the crystal structure prediction of flexible molecules is presented. It is applied to piracetam, whose conformational polymorphs exhibit a variety of hydrogen-bond motifs but lack the intramolecular hydrogen bond found in the gas-phase ab initio optimized conformer. Stable crystal packing can result when favourable intermolecular interactions are made possible when the molecule distorts from the gas-phase conformation. If the resulting intermolecular lattice energy is sufficiently favourable to compensate for the intramolecular energy penalty associated with the suboptimal gas-phase conformation, then the crystal structure may be experimentally feasible. The new approach involves searching for low-energy crystal structures using a large number of rigid conformers, firstly to systematically explore which regions of conformational space could give rise to low-energy hydrogen-bonded crystal structures, and then to refine the search using crystallographic insight to optimize particular intermolecular interactions. The timely discovery of a new polymorph (form IV) by an independent experimental team allowed this approach to be validated by way of a `blind test' of crystal structure prediction. Form IV was successfully identified as the most favourable computed crystal structure with a conformation very distinct from that in the previously known polymorphs.

On the Reaction of Hexachlorocyclotriphosphazene with Heptamethyldisilazane. Crystal Structure of P3N3Cl5{N(CH3)[Si(CH3)3]}

2007 ◽  
Vol 72 (10) ◽  
pp. 1407-1419 ◽  
Author(s):  
Radka Voznicová ◽  
Milan Alberti ◽  
Jan Taraba ◽  
Dalibor Dastych ◽  
Pavel Kubáček ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Dft Calculations ◽  
Crystal Structures ◽  
Elemental Analysis ◽  
Molar Ratio ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular And Crystal Structures

The reaction of P3N3Cl6 (1) with heptamethyldisilazane in the molar ratio 1:1 leads to the formation of 2,4,4,6,6-pentachloro-N-methyl-N-(trimethylsilyl)cyclotriphosphazen-2-amine, P3N3Cl5{N(CH3)[Si(CH3)3]} (2). Compound 2 was characterized by elemental analysis and spectroscopically. Molecular and crystal structures of 2 were determined by X-ray diffraction. 2 is monoclinic, space group P21/n. Experimental data were compared with results of DFT calculations.

scholarly journals Triphenylphosphine-(N,N-dimethyldithiocarbamato)-gold(I) Methanol Solvate

2017 ◽  
Author(s):  
Nicolas Bélanger-Desmarais ◽  
Christian Reber
Keyword(s):  
Crystal Structure ◽  
Raman Spectroscopy ◽  
Dft Calculations ◽  
Gas Phase ◽  
Experimental Spectrum ◽  
Frontier Molecular Orbitals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Single Complex ◽  
Good Agreement

A gold(I) complex with a triphenylphosphine and a monodentate N,N-dimethyldithiocarbamate ligand was synthesized and characterized by Raman spectroscopy and single crystal X-ray diffraction. DFT calculations (Gaussian 09, PBE1PBE/Lanl2dz) were undertaken for a single complex in the gas-phase. The DFT-optimized structure is in good agreement with the crystal structure and the DFT-calculated Raman spectrum also is in excellent agreement with the experimental spectrum. Assignments of the Raman peaks are based on these DFT calculations. Frontier molecular orbitals were calculated and their nature is discussed.

Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb2[(UO2)(Cr2O7)(NO3)2] and two new polymorphs of Rb2Cr3O10

2021 ◽  
Vol 236 (1-2) ◽  
pp. 11-21
Author(s):  
Evgeny V. Nazarchuk ◽  
Oleg I. Siidra ◽  
Dmitry O. Charkin ◽  
Stepan N. Kalmykov ◽  
Elena L. Kotova
Keyword(s):  
Crystal Structure ◽  
Aqueous Solutions ◽  
Crystal Structures ◽  
Hydrothermal Treatment ◽  
Ambient Conditions ◽  
Screw Axis ◽  
3D Framework ◽  
Solution Acidity

Abstract Three new rubidium polychromates, Rb2[(UO2)(Cr2O7)(NO3)2] (1), γ-Rb2Cr3O10 (2) and δ-Rb2Cr3O10 (3) were prepared by combination of hydrothermal treatment at 220 °C and evaporation of aqueous solutions under ambient conditions. Compound 1 is monoclinic, P 2 1 / c $P{2}_{1}/c$ , a = 13.6542(19), b = 19.698(3), c = 11.6984(17) Å, β = 114.326(2)°, V = 2867.0(7) Å3, R 1 = 0.040; 2 is hexagonal, P 6 3 / m $P{6}_{3}/m$ , a = 11.991(2), c = 12.828(3) Å, γ = 120°, V = 1597.3(5) Å3, R 1 = 0.031; 3 is monoclinic, P 2 1 / n $P{2}_{1}/n$ , a = 7.446(3), b = 18.194(6), c = 7.848(3) Å, β = 99.953(9)°, V = 1047.3(7) Å3, R 1 = 0.037. In the crystal structure of 1, UO8 bipyramids and NO3 groups share edges to form [(UO2)(NO3)2] species which share common corners with dichromate Cr2O7 groups producing novel type of uranyl dichromate chains [(UO2)(Cr2O7)(NO3)2]2−. In the structures of new Rb2Cr3O10 polymorphs, CrO4 tetrahedra share vertices to form Cr3O10 2− species. The trichromate groups are aligned along the 63 screw axis forming channels running in the ab plane in the structure of 2. The Rb cations reside between the channels and in their centers completing the structure. The trichromate anions are linked by the Rb+ cations into a 3D framework in the structure of 3. Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems is discussed.

scholarly journals Crystal Chemical Relations in the Shchurovskyite Family: Synthesis and Crystal Structures of K2Cu[Cu3O]2(PO4)4 and K2.35Cu0.825[Cu3O]2(PO4)4

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 807
Author(s):  
Ilya V. Kornyakov ◽  
Sergey V. Krivovichev
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structural Complexity ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Complexity Measures ◽  
X Ray ◽  
The Family ◽  
Similarities And Differences ◽  
Related Compounds

Single crystals of two novel shchurovskyite-related compounds, K2Cu[Cu3O]2(PO4)4 (1) and K2.35Cu0.825[Cu3O]2(PO4)4 (2), were synthesized by crystallization from gaseous phase and structurally characterized using single-crystal X-ray diffraction analysis. The crystal structures of both compounds are based upon similar Cu-based layers, formed by rods of the [O2Cu6] dimers of oxocentered (OCu4) tetrahedra. The topologies of the layers show both similarities and differences from the shchurovskyite-type layers. The layers are connected in different fashions via additional Cu atoms located in the interlayer, in contrast to shchurovskyite, where the layers are linked by Ca2+ cations. The structures of the shchurovskyite family are characterized using information-based structural complexity measures, which demonstrate that the crystal structure of 1 is the simplest one, whereas that of 2 is the most complex in the family.

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