scholarly journals Structural Studies of Iron(III) Complexes with N4O2 Coordination Sphere

2014 ◽  
Vol 70 (a1) ◽  
pp. C1230-C1230
Author(s):  
Mauricio Fuentealba ◽  
Deborah Gonzalez ◽  
Vania Artigas
Keyword(s):  
Intermolecular Interactions ◽  
High Spin State ◽  
External Perturbation ◽  
Crystal Structure Analysis ◽  
Remarkable Feature ◽  
Complex Processes ◽  
A Minor ◽  
Minor Distortion ◽  
Diamagnetic State ◽  
Solvate Molecule

The Spin-Crossover (SCO) phenomenon implicates a switchable between a low-spin (LS) diamagnetic state, which is stable at low temperatures and a paramagnetic high-spin state (HS), which is stable at higher temperatures. This transition is generated by an external perturbation such as temperature, pressure or light. In general, the switching process in solid-state systems is controlled by cooperative intermolecular interactions. The correlation of structure with physical properties is crucial to the identification of these interactions and ultimately the understanding of the complex processes that control the SCO phenomenon[1]. With the aim of developing new SCO materials, we carried out the syntheses and crystal structure analysis of seven iron(III) complexes, mixing 5-bromo-salicylaldehyde or 5-chloro-salicylaldehyde and ethylendiamine with iron(III) chloride and/or ammonium hexafluorophosphate solutions by slow diffusion or reflux in methanol or 2-propanol (figure 1). The crystal structures show the iron(III) centre is hexacoordinated (FeN4O2) and the coordination polyhedron can be described as a distorted octahedron formed by the 4 N atoms of the ethylenediamine fragment and 2 hydroxyl O atoms from the salicylaldehyde fragment, this distortion was evaluated at 120 and 298 K, the major distortion were observed in complexes [2]+ PF6–· MeOH, [2]+ PF6–·iPrOH and [1]+ PF6–·MeOH, which is characteristic in HS states, while the complexes [2]+ Cl–·iPrOH, [1]+ PF6–·iPrOH [2]+ and [2]+ClO4–, shows a minor distortion according to LS states. On the other hand, [1]+ClO4– is a SCO complex with a typical geometry for both spin states at 120 K (LS) and 298 K (HS). Finally, we studied the intermolecular interactions using Crystal Explorer Software[2] between the iron complexes, the counterion and/or the solvate molecule, for instance, in the [2]+PF6–·MeOH complex, the most remarkable feature observed are Br···Br intermolecular interactions (figure 2). ACKNOWLEDGMENTS: FONDECYT N01130640, FONDEQUIP EQM120095 and Beca CONICYT folio 21130944

Elaeocarpus alkaloids. I. The structures of (±)-elaeocarpine, (±)-isoelaeocarpine, and (±)-isoelaeocarpicine, three new indolizidine alkaloids from Elaeocarpus polydactylus

1969 ◽  
Vol 22 (4) ◽  
pp. 775 ◽  
Author(s):  
SR Johns ◽  
JA Lamberton ◽  
AA Sioumis ◽  
RI Willing
Keyword(s):  
Sodium Hydroxide ◽  
Sodium Hydroxide Solution ◽  
Acetyl Derivative ◽  
Spectroscopic Properties ◽  
Crystal Structure Analysis ◽  
Hydroxide Solution ◽  
Total Alkaloids ◽  
Ring Junction ◽  
Relative Stereochemistry ◽  
A Minor

Three new interrelated alkaloids have been isolated from Elaeocarpus poly-dactylus Schltr. (family Elaeocarpaceae). Two of these alkaloids, (�)-elaeocarpine (I) and (�)-isoelaeocarpine (II), are isomeric and the structure and complete stereochemistry of (�)-elaeocarpine have been established from an X-ray crystal structure analysis of (�)- elaeocarpine hydrobromide.1 From a detailed analysis of the spectroscopic properties of (�)-elaeocarpine and (�)-isoelaeocarpine, and in particular of their 100-Mc/s n.m.r. spectra, it has been shown that the alkaloids are epimeric at C7 and that (�)-isoelaeocarpine has a cis ring junction at C7,C8, whereas (�)-elaeocarpine is known to have a C7,C8 trans configuration. In methanolic sodium hydroxide solution (�)-elaeocarpine and (�)-isoelaeocarpine are interconvertible. (�)-Isoelaeocarpicine (VIa) is closely related to (�)-elaeocarpine and (�)-iso-elaeocarpine, and has been so named because the configuration at C7,C8 corresponds to that of (�)-isoelaeocarpine. (+)- Isoelaeocarpicine is phenolic, differs from (�)-elaeocarpine and (�)- isoelaeocarpine in molecular composition by the elements of water, and is converted into a mixture of elaeocarpine and isoelaeocarpine by the action of methanolic sodium hydroxide solution. Study of the 100-Mc/s n.m.r. spectrum of (+)-isoelaeocarpicine has established the complete stereochemistry shown in (VIa). The structures indicated for the three alkaloids (I), (II), and (VIa) depict relative stereochemistry only and are not intended to imply a particular absolute configuration. Study of the reaction between (+)-isoelaeocarpicine (VIa) and acetic anhydride shows that an O-acetyl derivative (VIb) is formed rapidly, but that with longer reaction periods the amide (VIIIa) is obtained. The steric requirements of the borohydride reduction of (I) and (II) have been studied, and it has been found that the n.m.r. spectra of solutions of the alcohol (XIIa) in CD3CO2D or of its hydro- chloride in CD3OD indicate an equilibrium between two deuteronated forms of (XIIa), one of which is considered to have a cis and the other a trans ring junction for the indolizidine ring. A minor alkaloid, C17H21N3, amounts to <1% of the total alkaloids, and a minor non-alkaloidal constituent has been identified as 2- hydroxy-6-methylacetophenone.

Structural elucidation and study of intermolecular interactions in meso-tetratolylporphyrins

2016 ◽  
Vol 20 (07) ◽  
pp. 833-842
Author(s):  
Rahul Soman ◽  
Subramaniam Sujatha ◽  
Chellaiah Arunkumar
Keyword(s):  
Surface Analysis ◽  
Intermolecular Interactions ◽  
Crystal Packing ◽  
Crystal Structure Analysis ◽  
Hirshfeld Surface ◽  
Hirshfeld Surface Analysis ◽  
Axial Position ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
Porphyrin Core

Synthesis and crystal structure analysis of meso-tetratolylporphyrins, 1–5 combined with computational Hirshfeld surface analysis were investigated. The crystal packing of porphyrins 1, 3 and 4 are arranged in an “orthogonal fashion” whereas 2 and 5 are in a “slip-stack or off-set fashion” through various intermolecular interactions. Compound 2 exhibits saddle geometry whereas 5 showed a domed geometry as evident from the single crystal X-ray diffraction studies. The enhancement of non-planarity in 2 is probably due to the presence of numerous intermolecular interactions caused by the presence of trifluoroacetate anions on both faces of the porphyrin in addition to the bulky bromine groups at the [Formula: see text]-pyrrole positions. In 5, the non-planarity is merely due to the metal coordination at the porphyrin core as pentacoordinated Mn[Formula: see text] center with a chloro ligand in the axial position. Hirshfeld surface analysis was performed in order to analyze the various intermolecular interactions present in these porphyrins and the result was discussed.

scholarly journals Retrotransposition and Cell-to-Cell Transfer of Foamy Viruses

2003 ◽  
Vol 77 (21) ◽  
pp. 11855-11858 ◽  
Author(s):  
Martin Heinkelein ◽  
Matthias Rammling ◽  
Thomas Juretzek ◽  
Dirk Lindemann ◽  
Axel Rethwilm
Keyword(s):  
High Efficiency ◽  
Transmembrane Protein ◽  
Foamy Virus ◽  
Marker Gene ◽  
Cell Transfer ◽  
Remarkable Feature ◽  
Initial Report ◽  
A Cell ◽  
A Minor ◽  
Cell To Cell Transfer

ABSTRACT A remarkable feature of the prototype foamy virus (PFV) replication pathway has been reported to consist of the ability to retrotranspose intracellularly with high efficiency (M. Heinkelein, T. Pietschmann, G. Jármy, M. Dressler, H. Imrich, J. Thurow, D. Lindemann, M. Bock, A. Moebes, J. Roy, O. Herchenröder, and A. Rethwilm, EMBO J. 19:3436-3345, 2000). PFV intracellular retrotransposition (IRT) was reported to be enhanced by coexpression of fusion-defective envelope protein. To investigate the possibility of cell-to-cell transfer of PFV genomes, which could mimic IRT, we performed cocultivation experiments with cells transfected with an IRT-competent and marker gene-expressing PFV vector together with cells expressing a different marker and measured cells positive for both markers. The findings corroborated the initial report on IRT of Env-deficient PFV. Furthermore, they indicated that viral cores that have incorporated fusion-deficient Env can be transferred from cell to cell in a cell type-specific manor. One possible explanation consists of a minor alternative cleavage site in Env that can be used to expose the fusion peptide of the Env transmembrane protein, which appears to be required for virus uptake.

scholarly journals Tetrakis[μ3-2-(piperidin-1-yl)ethanolato]tetrakis[chloridocopper(II)]

2014 ◽  
Vol 70 (5) ◽  
pp. m194-m194
Author(s):  
Mei Luo ◽  
Yong-Hua Huang ◽  
Jing-Cheng Zhang
Keyword(s):  
Intermolecular Interactions ◽  
Minor Component ◽  
Chair Conformation ◽  
Hydroxyl Groups ◽  
Tetranuclear Complex ◽  
Pyramidal Geometry ◽  
A Minor ◽  
Square Pyramidal Geometry

In the title tetranuclear compound, [Cu4(C7H14NO)4Cl4], each CuIIcation isN,O-chelated by a piperidineethanolate anion and coordinated by a Cl−anion and two O atoms from neighboring piperidineethanolate anions in a distorted NO3Cl square-pyramidal geometry. The deprotonated hydroxyl groups of the piperidineethanolate anions bridge CuIIcations, forming the tetranuclear complex. All piperidine rings display a chair conformation. In the crystal, there are no significant intermolecular interactions present. The crystal studied was an inversion twin refined with a minor component of 0.18 (5).

scholarly journals Weak Intermolecular Interactions in a Series of Bioactive Oxazoles

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 3024
Author(s):  
Anita M. Grześkiewicz ◽  
Tomasz Stefański ◽  
Maciej Kubicki
Keyword(s):  
Intermolecular Interactions ◽  
Crystal Packing ◽  
Topological Analysis ◽  
Minor Role ◽  
X Ray Diffraction ◽  
Weak Intermolecular Interactions ◽  
Nonspecific Interactions ◽  
Molecule Interactions ◽  
A Minor ◽  
Divalent Sulfur

The intermolecular interactions in a series of nine similar 4,5-phenyl-oxazoles were studied on the basis of crystal structures determined by X-ray diffraction. The crystal architectures were analyzed for the importance and hierarchies of different, weak intermolecular interactions using three approaches: the geometrical characteristics, topological analysis (for the model based on the transfer of multipolar parameters), and energetics of the molecule–molecule interactions. The geometries of the molecules were quite similar and close to the typical values. The results of the analysis of the interactions suggest that the number of nonspecific interactions is more important than the apparent strength of the specific interactions. The interactions involving covalently bound bromine and divalent sulfur atoms were classified as secondary, they certainly did not define the crystal packing, and they played a minor role in the overall crystal cohesion energies. Incidentally, another method for confirming the degree of isostructurality, according to the topologies of the interactions, is described.

Crystal structures of (Ba1−xLax)[Mg(1+x)/3Nb(2−x)/3]O3 with 0.9 ≤ x ≤ 1.0

2003 ◽  
Vol 18 (4) ◽  
pp. 1003-1010 ◽  
Author(s):  
Hyun Min Park ◽  
Hwack Joo Lee ◽  
Yang Koo Cho ◽  
Sahn Nahm
Keyword(s):  
Single Phase ◽  
Weight Fraction ◽  
Crystal Structure Analysis ◽  
Structure Model ◽  
X Ray Diffraction ◽  
Minor Phase ◽  
Two Phase ◽  
Rietveld Refinements ◽  
The Matrix ◽  
A Minor

Based on a structure model of mixture of phases, the crystal structure analysis of (Ba1−xLax)[Mg(1+x)/3Nb(2−x)/3]O3 (BLMN) (x = 0.9 and 1.0) by Rietveld refinements was carried out. The pure La(Mg2/3Nb1/3)O3 (LMN) and BLMN (x=0.9) actually consist of a two-phase mixture rather a single phase. One is Fm-3m, which is cubic and 1:1 ordered and the other is P21/n, which is monoclinic and has both 1:1 ordering and the antiphase and inphase tilting of oxygen octahedra with a−a−c+. The weight fraction of the Fm-3m phase is 17.5% at x=0.9 and further decreases to 7.5% in pure LMN. Meanwhile, that of the P21/n phase is 82.5% at x =0.9 and further increases to 92.5% in pure LMN. The I4/m phase, which is present as a minor phase from x=0.3 to 0.7, disappeared when x≥0.9. The abrupt change of the x-ray diffraction pattern at x=0.9 is caused by a change of major phase from Fm-3m to P21/n phase in the matrix.

scholarly journals N′-(1,3-Benzothiazol-2-yl)benzenesulfonohydrazide: crystal structure, Hirshfeld surface analysis and computational chemistry

2019 ◽  
Vol 75 (4) ◽  
pp. 516-523
Author(s):  
Thomas C. Baddeley ◽  
Marcus V. N. de Souza ◽  
James L. Wardell ◽  
Mukesh M. Jotani ◽  
Edward R. T. Tiekink
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Intermolecular Interactions ◽  
Torsion Angles ◽  
Axis Direction ◽  
Compound C ◽  
Phenyl Rings ◽  
Independent Molecules ◽  
The Individual ◽  
A Minor

The asymmetric unit of the title compound, C13H11N3O2S2, comprises two independent molecules (A and B); the crystal structure was determined by employing synchrotron radiation. The molecules exhibit essentially the same features with an almost planar benzothiazole ring (r.m.s. deviation = 0.026 and 0.009 Å for A and B, respectively), which forms an inclined dihedral angle with the phenyl ring [28.3 (3) and 29.1 (3)°, respectively]. A difference between the molecules is noted in a twist about the N—S bonds [the C—S—N—N torsion angles = −56.2 (5) and −68.8 (5)°, respectively], which leads to a minor difference in orientation of the phenyl rings. In the molecular packing, A and B are linked into a supramolecular dimer via pairwise hydrazinyl-N—H...N(thiazolyl) hydrogen bonds. Hydrazinyl-N—H...O(sulfonyl) hydrogen bonds between A molecules assemble the dimers into chains along the a-axis direction, while links between centrosymmetrically related B molecules, leading to eight-membered {...HNSO}2 synthons, link the molecules along [001]. The result is an undulating supramolecular layer. Layers stack along the b-axis direction with benzothiazole-C—H...O(sulfonyl) points of contact being evident. The analyses of the calculated Hirshfeld surfaces confirm the relevance of the above intermolecular interactions, but also serve to further differentiate the weaker intermolecular interactions formed by the independent molecules, such as π–π interactions. This is also highlighted in distinctive energy frameworks calculated for the individual molecules.

Quantitative Crystal Structure Analysis of (E)-1-[(2-Chloro-1,3-thiazol-5-yl)methyl]-3-methyl-2-nitroguanidine

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Dhananjay Dey ◽  
Chetan S. Shripanavar ◽  
Kaushik Banerjee ◽  
Deepak Chopra
Keyword(s):  
Crystal Structure ◽  
Intermolecular Interactions ◽  
Molecular Conformation ◽  
Crystal Packing ◽  
Lattice Energy ◽  
Crystal Structure Analysis ◽  
Hirshfeld Surface ◽  
Biologically Active ◽  
Molecular Formula ◽  
Periodic Calculations

The crystal structure of a biologically active (E)-1-[(2-chloro-1,3-thiazol-5-yl)methyl)]-3-methyl-2-nitroguanidine with molecular formula C6H8N5O2ClS has been investigated based on the molecular conformation and the supramolecular packing in terms of intermolecular interactions involving N–H⋯O, N–H⋯N, and C–H⋯O–N (nitro group), C–H⋯N (thiazol) hydrogen bonds, offset π–π stacking, C–H⋯π and N(–NO2)⋯C=N intermolecular interactions. Furthermore, a short C–Cl⋯O–N contact is also present which contributes towards the crystal packing. The lattice energy of the title compound has been calculated using the PIXEL approach (the Coulomb-London-Pauli (CLP) model) and compared with periodic calculations performed using CRYSTAL09. In addition, Hirshfeld surface analysis and fingerprint plots provide a platform for the evaluation of the contribution of different intermolecular interactions towards the packing behaviour.

scholarly journals 2D Layer Arrangement of Solely [HS-HS] or [LS-LS] Molecules in the [HS-LS] State of a Dinuclear Fe(II) Spin Crossover Complex

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 448
Author(s):  
Fabian Fürmeyer ◽  
Luca M. Carrella ◽  
Eva Rentschler
Keyword(s):  
Crystal Structure ◽  
Spin Crossover ◽  
Crystal Packing ◽  
Spin Transition ◽  
High Spin State ◽  
Crystal Structure Analysis ◽  
Magnetic Data ◽  
The Novel ◽  
Layer Arrangement ◽  
Dinuclear Iron

Herein we report the synthesis and characterization of three new dinuclear iron(II) complexes [FeII2(I4MTD)2](F3CSO3)4 (C1), [FeII2(I4MTD)2](ClO4)4 (C2) and [FeII2(I4MTD)2](BF4)4 (C3) based on the novel ligand (I4MTD = 2,5-bis{[(1H-imidazol-4-ylmethyl)amino]methyl}-1,3,4-thiadiazole). Magnetic susceptibility measurements and single-crystal structure analysis show that the iron(II) spin centers for all complexes are in the high spin state at high temperatures. While the magnetic data of air-dried samples confirm the [HS-HS] state for C1 and C2 down to very low temperature, for C3, a gradual spin crossover is observed below 150 K. The crystal structure of C3·THF at 100 K shows that a spin transition from [HS-HS] to an intermediate state takes place, which is a 1:1 mixture of discrete [HS-HS] and [LS-LS] molecules, as identified unambiguously by crystallography. The different SCO properties of C1–C3 can be attributed to crystal packing effects in the solid state.

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