At last! The single-crystal X-ray structure of a naturally occurring sample of the ilmenite-type oxide FeCrO3

2015 ◽  
Vol 71 (5) ◽  
pp. 555-561 ◽  
Author(s):  
María Ana Pérez-Cruz ◽  
María de la Paz Elizalde-González ◽  
Roberto Escudero ◽  
Sylvain Bernès ◽  
Rutilo Silva-González ◽  
...  
Keyword(s):  
Single Crystal ◽  
Density Functional ◽  
Limit Of Detection ◽  
Structural Type ◽  
Crystallographic Axis ◽  
Functional Theory ◽  
Actual Structure ◽  
Vacancy Defects ◽  
X Ray ◽  
Opencast Mine

A natural single crystal of the ferrimagnetic oxide FeCrO3, which was found in an opencast mine situated in the San Luis Potosí State in Mexico, has been characterized in order to elucidate some outstanding issues about the actual structure of this material. The single-crystal X-ray analysis unambiguously shows that transition metal cations are segregated in alternating layers normal to the threefold crystallographic axis, affording a structure isomorphous to that of ilmenite (FeTiO3), in the space group R \overline{3}. The possible occurrence of cation antisite and vacancy defects is below the limit of detection available from X-ray data. Structural and magnetic results are in agreement with the coherent slow intergrowth of magnetic phases provided by the two antiferromagnetic corundum-type parent oxides Fe2O3(hematite) and Cr2O3(eskolaite). Our results are consistent with the most recent density functional theory (DFT) studies carried out on digital FeCrO3[Sadat Nabi & Pentcheva (2011).Phys. Rev. B,83, 214424], and suggest that synthetic samples of FeCrO3might present a cation distribution different to that of the ilmenite structural type.

Quantitative Analysis of Intermolecular Interactions in 3‐Cyano‐2‐Pyridones: Evaluation through Single Crystal X‐ray Diffraction and Density Functional Theory

2018 ◽  
Vol 3 (21) ◽  
pp. 5864-5873
Author(s):  
Sunil K. Rai ◽  
Tomasz Sierański ◽  
Shaziya Khanam ◽  
Krishnan Ravi Kumar ◽  
Balasubramanian Sridhar ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Quantitative Analysis ◽  
Single Crystal ◽  
Intermolecular Interactions ◽  
Density Functional ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray

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.

Structures of cefradine dihydrate and cefaclor dihydrate from DFT-D calculations

2013 ◽  
Vol 69 (11) ◽  
pp. 1229-1233 ◽  
Author(s):  
Jacco van de Streek ◽  
Jukka Rantanen ◽  
Andrew D. Bond
Keyword(s):  
Single Crystal ◽  
Density Functional ◽  
Room Temperature ◽  
Partial Information ◽  
Structural Data ◽  
Pharmaceutical Sciences ◽  
Crystal Data ◽  
Functional Theory ◽  
X Ray ◽  
Atomic Coordinates

The crystal structure of cefradine dihydrate, C16H19N3O4S·2H2O, is considered in the pharmaceutical sciences to be the epitome of an isolated-site hydrate. The structure from single-crystal X-ray data was described in 1976, but atomic coordinates were not published. The atomic coordinates are determined here by combining the information available from the published single-crystal data with a dispersion-corrected density functional theory (DFT-D) method that has been validated to reproduce molecular crystal structures very accurately. Additional proof for the correctness of the structure comes from comparison with cefaclor dihydrate, C15H14ClN3O4S·2H2O, which is isomorphous and for which more complete single-crystal data are available. H-atom positions have not previously been published for either compound. The DFT-D calculations confirm that both cefradine and cefaclor are present in the zwitterionic form in the two dihydrate structures. A potential ambiguity concerning the orientation of the cyclohexadienyl ring in cefradine dihydrate is also clarified, and on the basis of the calculated energies it is shown that disorder should not be expected at room temperature. The DFT-D methods can be applied to recover full structural data in cases where only partial information is available, and where it may not be possible or desirable to obtain new experimental data.

scholarly journals Ab initio and DFT study on Cu (II) complex salicylate derivative

2014 ◽  
Vol 70 (a1) ◽  
pp. C1442-C1442
Author(s):  
Karthikeyan Natarajan ◽  
Sathya Duraisamy ◽  
Sivakumar Kandasamy
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray

X -ray diffraction becomes a routine process these decades for determining crystal structure of the materials. Most of the crystal structures solved nowadays is based on single crystal X-ray diffraction because it solves the crystal and molecular structures from small molecules to macro molecules without much human intervention. However it is difficult to grow single crystals of sufficient size and quality for conventional single-crystal X-ray diffraction studies. In such cases it becomes essential that structural information can be determined from powder diffraction data. With the recent developments in the direct-space approaches for structure solution, ab initio crystal structure analysis of molecular solids can be accomplished from X-ray powder diffraction data. It should be recalled that crystal structure determination from laboratory X-ray powder diffraction data is a far more difficult task than that of its single-crystal counterpart, particularly when the molecule possesses considerable flexibility or there are multiple molecules in the asymmetric unit. Salicylic acid and its derivatives used as an anti-inflammatory drug are known for its numerous medicinal applications. In our study, we synthesized mononuclear copper (II) complex of salicylate derivative. The structural characterization of the prepared compound was carried out using powder X-ray diffraction studies. Crystal structure of the compound has been solved by direct-space approach and refined by a combination of Rietveld method using TOPAS Academic V4.1. Density Functional Theory (DFT) calculations have to be carried in the solid state for the compound using GaussianW9.0 in the frame work of a generalized-gradient approximation (GGA). The geometry optimization was to be performed using B3LYP density functional theory. The atomic coordinates were taken from the final X-ray refinement cycle.

Origin of the chemical stability of phosphine-phosphoramidites: structural study of an UPPhos-type crystal and application of UPPhos in the asymmetric hydrogenation of imines

2017 ◽  
Vol 73 (8) ◽  
pp. 632-637
Author(s):  
Szabolcs Balogh ◽  
Gergely Farkas ◽  
Tamás Holczbauer ◽  
József Bakos
Keyword(s):  
Single Crystal ◽  
Chemical Stability ◽  
Density Functional ◽  
Asymmetric Hydrogenation ◽  
Iridium Complexes ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Asymmetric Catalytic ◽  
Type Crystal

Phosphine–phosphoramidites (PPAs) are heterobidentate ligands that have been developed in the last two decades and have been used successfully in asymmetric catalytic reactions. A single crystal of the PPA (11bS)-N-[(2S,4S)-4-(diphenylphosphanyl)pentan-2-yl]-N-methyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine, C38H35NO2P2, was prepared and structurally characterized by single-crystal X-ray diffraction and density functional theory (DFT) calculations. Structure elucidation revealed unique features which might have a significant effect in the excellent chemical stability of this type of molecule. The conformation of the molecule provides an optimal chelating structure. Iridium complexes of UPPhos were found to be efficient catalysts in the asymmetric hydrogenation of imines {UPPhos is (11bS)-N-[(2S,4S)-4-(diphenylphosphanyl)pentan-2-yl]-N-(propan-2-yl)dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepin-4-amine}.

scholarly journals Synthesis Single Crystal X-ray Structure DFT Studies and Hirshfeld Analysis of New Benzylsulfanyl-Triazolyl-Indole Scaffold

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 685 ◽  
Author(s):  
Ahmed T. A. Boraei ◽  
Saied M. Soliman ◽  
Sammer Yousuf ◽  
Assem Barakat
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Single Crystal ◽  
13C Nmr ◽  
Density Functional ◽  
Chemical Shifts ◽  
Functional Theory ◽  
X Ray ◽  
Reactivity Descriptors ◽  
Hirshfeld Analysis

Benzylsulfanyl-triazolyl-indole scaffold was synthesized through coupling of 4-amino-5-(1H-indol-2-yl)-1,2,4-triazol-3(2H)-thione and benzyl bromide in EtOH under basic conditions (K2CO3). The benzylation direction was deduced from the 13C NMR signal found at 35.09 ppm, assigned for the methylene carbon of the benzyl group, this value indicates that the benzyl group attacks sulfur, not nitrogen. 1H NMR, 13C NMR, COSY, HMQC, HRMS and X-ray single crystal diffraction analysis were used for structure assignment. The desired compound accomplished in good yield. Hirshfeld analysis revealed the importance of the short N...H (1.994–2.595 Ǻ), S…H (2.282 Ǻ) and C…H (2.670 Ǻ) contacts as well as the weak π-π stacking interactions in the molecular packing of benzylthio-triazolyl-indole scaffold. Its electronic and structural aspects were predicted using density functional theory (DFT) calculations and the reactivity descriptors as well. The Uv-Vis spectral bands were assigned based on the time-dependant density functional theory TD-DFT calculations, while the gauge-including atomic orbitals (GIAO) method was used to predict the 1H and 13C NMR chemical shifts.

Structural assignment of a bis-cyclopentenyl-β-cyanohydrin formedviaalkene metathesis from either a triene or a tetraene precursor

2013 ◽  
Vol 69 (11) ◽  
pp. 1207-1211 ◽  
Author(s):  
Keith G. Andrews ◽  
Christopher S. Frampton ◽  
Alan C. Spivey
Keyword(s):  
Density Functional Theory ◽  
Single Crystal ◽  
Natural Product ◽  
Density Functional ◽  
Major Product ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Crystallography ◽  
Structural Assignment ◽  
Nmr Prediction

The identity of the major product of Ru-catalysed alkene metathesis of two polyene substrates has been determined using density functional theory (DFT) NMR prediction, a1H–1H Total Correlated Spectroscopy (TOCSY) NMR experiment and ultimately by single-crystal X-ray crystallography. The substrates were designed as those that would potentially allow expedient access to thetrans-decalin skeleton of the natural product (−)-euonyminol, but the product was found to be a bis-cyclopentenyl-β-cyanohydrin [1-(1-hydroxycyclopent-3-en-1-yl)cyclopent-3-ene-1-carbonitrile, C11H13NO] rather than thetrans-2,3,6,7-dehydrodecalin-β-cyanohydrin.

scholarly journals Ba3CrN3H: A New Nitride-Hydride with Trigonal Planar Cr4+

2018 ◽  
Author(s):  
Nathaniel W. Falb ◽  
Jennifer N. Neu ◽  
Tiglet Besara ◽  
Jeffrey B. Whalen ◽  
David J. Singh ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Single Crystal ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Crystal Synthesis

Single crystal synthesis of a new nitride-hydride Ba3CrN3H. X-ray diffraction, nuclear magnetic resonance, and bond-valance sum and density functional theory calculations confirmed the presence and location of the anionic hydrogen in this compound.

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