Crystal structure of bis{(3,5-dimethylpyrazol-1-yl)dihydro[3-(pyridin-2-yl)pyrazol-1-yl]borato}iron(II)

The structure determination of [Fe(C13H15BN5)2] was undertaken as part of a project on the modification of the recently published spin-crossover (SCO) complex [Fe{H2B(pz)(pypz)}2] (pz = pyrazole, pypz = pyridylpyrazole). To this end, a new ligand was synthesized in which two additional methyl groups are present. Its reaction with iron trifluoromethanesulfonate led to a pure sample of the title compound, as proven by X-ray powder diffraction. The asymmetric unit consists of one complex molecule in a general position. The FeII atom is coordinated by two tridentate N-binding {H2B(3,5-(CH3)2-pz)(pypz)}− ligands. The Fe—N bond lengths range between 2.1222 (13) and 2.3255 (15) Å, compatible with FeII in the high-spin state, which was also confirmed by magnetic measurements. Other than a very weak C—H...N non-classical hydrogen bond linking individual molecules into rows extending parallel to [010], there are no remarkable intermolecular interactions.

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Crystal structure of bis(5-bromo-1,10-phenanthroline-κ2 N,N′)bis[dihydrobis(pyrazol-1-yl)borato-κ2 N 2,N 2′]iron(II) toluene disolvate

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989020010361 ◽

2020 ◽

Vol 76 (8) ◽

pp. 1398-1402

Author(s):

Sascha Ossinger ◽

Christian Näther ◽

Felix Tuczek

Keyword(s):

Spin Crossover ◽

Magnetic Measurements ◽

Complex Molecule ◽

Asymmetric Unit ◽

Acta Cryst ◽

Complex Molecules ◽

Borate Complexes ◽

Solvent Molecules ◽

Phenanthroline Ligands

The structure determination of the title compound was undertaken as part of a project on the modification and synthesis of new spin-crossover (SCO) compounds based on octahedral FeII bis(pyrazolyl)borate complexes. In the course of these investigations, the compound [Fe(C6H8BN4)2(C12H7BrN2)] was synthesized, for which magnetic measurements revealed an incomplete spin-crossover behaviour. Crystallization of this compound from toluene led to the formation of crystals of the toluene disolvate, [Fe(C6H8N4B)2(C12H7N2Br)]·2C7H8. Its asymmetric unit comprises two discrete metal complex molecules and two toluene solvent molecules. One of the latter is severely disordered and its contribution to the diffracted intensities was removed using the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18]. In each complex molecule, the FeII cation is coordinated by the two N atoms of a 5-bromo-1,10-phenanthroline ligand and by two pairs of N atoms of chelating dihydrobis(pyrazol-1-yl)borate ligands in the form of a slightly distorted octahedron. The discrete complexes are arranged in columns along the a-axis direction with the toluene solvate molecules located between the columns. The 5-bromo-1,10-phenanthroline ligands of neighbouring columns are approximately parallel and are slightly shifted relative to each other, indicating π–π interactions.

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Spin State Behavior of A Spin-Crossover Iron(II) Complex with N,N′-Disubstituted 2,6-bis(pyrazol-3-yl)pyridine: A Combined Study by X-ray Diffraction and NMR Spectroscopy

Crystals ◽

10.3390/cryst10090793 ◽

2020 ◽

Vol 10 (9) ◽

pp. 793

Author(s):

Elizaveta K. Melnikova ◽

Dmitry Yu. Aleshin ◽

Igor A. Nikovskiy ◽

Gleb L. Denisov ◽

Yulia V. Nelyubina

Keyword(s):

Nmr Spectroscopy ◽

Spin State ◽

Metal Ion ◽

Spin Crossover ◽

Molecular Design ◽

Chemical Shifts ◽

Variable Temperature ◽

High Spin State ◽

X Ray Diffraction ◽

X Ray

A series of three different solvatomorphs of a new iron(II) complex with N,N′-disubstituted 2,6-bis(pyrazol-3-yl)pyridine, including those with the same lattice solvent, has been identified by X-ray diffraction under the same crystallization conditions with the metal ion trapped in the different spin states. A thermally induced switching between them, however, occurs in a solution, as unambiguously confirmed by the Evans technique and an analysis of paramagnetic chemical shifts, both based on variable-temperature NMR spectroscopy. The observed stabilization of the high-spin state by an electron-donating substituent contributes to the controversial results for the iron(II) complexes of 2,6-bis(pyrazol-3-yl)pyridines, preventing ‘molecular’ design of their spin-crossover activity; the synthesized complex being only the fourth of the spin-crossover (SCO)-active kind with an N,N′-disubstituted ligand.

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A new Co(II) coordination polymer with the 2-(4-pyridyl)-terephthalate ligand: synthesis, crystal structure and magnetic properties

Zeitschrift für Naturforschung B ◽

10.1515/znb-2019-0096 ◽

2019 ◽

Vol 74 (7-8) ◽

pp. 619-622

Author(s):

Danian Tian ◽

Runmei Ding ◽

Bingbing Chen ◽

Peipei Cen

Keyword(s):

Magnetic Measurements ◽

Layer Structure ◽

Octahedral Geometry ◽

Supramolecular Network ◽

Asymmetric Unit ◽

Temperature Dependent ◽

X Ray ◽

Hydrogen Bonding Interactions ◽

Bimetallic Layer ◽

Ferromagnetic Interactions

AbstractA new Co(II) complex, [Co(pta)(H2O)2]n (1), with the 2-(4-pyridyl)-terephthalate ligand (pta2−) has been synthesized and structurally and magnetically characterized. Single crystal X-ray analysis indicates that the unique Co(II) ion in the asymmetric unit of 1 displays stretched octahedral geometry. Compound 1 presents a bimetallic layer structure which is further expanded to a 3D supramolecular network through hydrogen bonding interactions. Magnetic measurements have revealed the temperature-dependent existence of antiferromagnetic and ferromagnetic interactions in compound 1.

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The structure determination of rabbit phosphoglucomutase

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1981.0073 ◽

1981 ◽

Vol 293 (1063) ◽

pp. 205-208 ◽

Cited By ~ 5

Keyword(s):

Heavy Atom ◽

Partial Solution ◽

Relative Molecular Mass ◽

Asymmetric Unit ◽

X Ray Diffraction ◽

X Ray ◽

Tetragonal Crystals ◽

Glycol Solution ◽

Rotation Function

Tetragonal crystals of rabbit phosphoglucomutase have been grown from solutions containing ammonium sulphate, polyethylene glycol solution and enzyme. There are two molecules, each of relative molecular mass 64 000 per asymmetric unit. A rotation function suggests that these are related by a twofold axis. X-ray diffraction data for five heavy-atom derivatives and native crystals have been collected by using oscillation photography. A tentative and partial solution of the KAu(CN) 2 sites has been obtained. The enzyme in the native crystals is phosphorylated, but the phosphate can be removed without harm to the crystals. Similarly the essential Mg 2+ ion can be removed or replaced by Zn 2+ . The enzyme is active in the native crystals.

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4,4′-Bithiazoles as Ligands: Crystal and Molecular Structure of bis(O,O′-Nitrato)(2,2′-diphenyl-4,4′-bithiazole)copper(II) (Two Polymorphs)

Australian Journal of Chemistry ◽

10.1071/ch03016 ◽

2003 ◽

Vol 56 (9) ◽

pp. 949 ◽

Cited By ~ 3

Author(s):

S. Ali Asghar Torabi ◽

Fahimeh Jamali ◽

George A. Koutsantonis ◽

Ali Morsali ◽

Brian W. Skelton ◽

...

Keyword(s):

Molecular Structure ◽

Low Temperature ◽

Molecular Complex ◽

Structure Determination ◽

Crystal And Molecular Structure ◽

Plane Angle ◽

Asymmetric Unit ◽

X Ray ◽

Crystallographic Symmetry

A low-temperature single-crystal X-ray structure determination of the 1 : 1 adduct of copper(II) nitrate with 2,2′-diphenyl-4,4′-bithiazole (L) shows it to be a molecular complex with L behaving as a symmetrical N,N′ chelate, and the nitrate groups as unsymmetrical O,O′ chelates: [LCu(O2NO)2]. Two polymorphs, both monoclinic P21/c, have been obtained from acetonitrile (‘α’) and methanol (‘β’), respectively, with one molecule, devoid of crystallographic symmetry, in the asymmetric unit of each structure. The copper environments are distorted planar four-coordinate, cis-N2CuO2 (Cu–N 2.011(1), 1.973(1), Cu–O 1.995(1), 1.962(1) Å), ‘in-plane’ angle sum Σ 369.5°, with longer trans, axial contacts (Cu–O 2.455(1), 2.458(2) Å) for the α-form; respective values are 1.995(5), 1.991(4), 1.997(4), 1.973(3) Å, 360.4°, 2.500(4), and 2.396(4) Å for the β-form.

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Six pyrimidonium salts: determination of their crystal structures and studies of their prototropic behaviour in solution

Canadian Journal of Chemistry ◽

10.1139/v84-195 ◽

1984 ◽

Vol 62 (6) ◽

pp. 1194-1202 ◽

Cited By ~ 7

Author(s):

Thomas W. S. Lee ◽

Steven J. Rettig ◽

Ross Stewart ◽

James Trotter

Keyword(s):

Hydrogen Exchange ◽

Molecular Geometry ◽

High Reactivity ◽

Methyl Groups ◽

Contributing Factors ◽

X Ray ◽

X Ray Crystallography ◽

Reactive Compound ◽

Chloride Salts

Six methyl-substituted 2-pyrimidonium chloride salts have been prepared and the rates of hydrogen exchange of their reactive methyl groups (at the 4- and 6-positions) have been determined in DCl/D2O solution. Adjacent methyl groups, whether on nitrogen or carbon, activate the exchanging centres, whereas more distant methyl groups have a deactivating effect. The molecular geometry of the salts has been determined by X-ray crystallography with the view to determining whether the presence of strain in the pyrimidonium ring can account for the activating effect of adjacent methyl. The most reactive compound, the 1,5,6-trimethylpyrimidonium chloride, has a geometry that is consistent with high reactivity, viz. a non-planar ring and short H … H intermethyl distance. However, the 1,4,5,6-tetramethyl compound, which also is non-planar and has an extremely short 5-6 intermethyl distance (1.99 Å), is not highly reactive; that is, the heightened strain is unable to overcome the deactivating inductive effect of the additional methyl group. We conclude that deviations from ring planarity and short intermethyl distances are insufficient to account for the activation produced by adjacent methyl though they appear to be contributing factors to this effect.

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Magnetostructural Relationships For Fe(III) Spin Crossover Complexes

Nova Biotechnologica et Chimica ◽

10.1515/nbec-2015-0019 ◽

2015 ◽

Vol 14 (1) ◽

pp. 96-103 ◽

Cited By ~ 1

Author(s):

Peter Augustín ◽

Roman Boča

Keyword(s):

Spin Crossover ◽

Pearson Correlation ◽

Principal Component ◽

High Spin State ◽

Structural Data ◽

Multivariate Methods ◽

Schiff Base Ligands ◽

Thermally Induced ◽

X Ray ◽

Magnetization Data

Abstract Structural data for fifteen complexes of Fe(III) of a general formula [FeL5X], with pentadentate Schiff-base ligands L5 and unidentate coligands X−, were subjected to a statistical analysis. The multivariate methods such as Pearson correlation, cluster analysis and principal component analysis split the data into two clusters depending upon the low-spin and/or high-spin state of the complex at the temperature of the X-ray experiment. Some of these complexes exhibit a thermally induced spin crossover. The numerical analysis of the magnetic susceptibility and magnetization data for an enlarged set of Fe(III) spin crossover systems yields the enthalpy ΔH and entropy ΔS of the transition along with the transition temperature T1/2 and the solid state cooperativeness. The thermodynamic data show a mutual relationship manifesting itself by linear ΔS vs ΔH and T1/2 vs ΔH correlations.

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A Promising New Schiff Base-like Ligand for the Synthesis of Octahedral Iron(II) Spin Crossover Complexes

Zeitschrift für Naturforschung B ◽

10.1515/znb-2010-0315 ◽

2010 ◽

Vol 65 (3) ◽

pp. 323-328 ◽

Cited By ~ 17

Author(s):

Wolfgang Bauer ◽

Tanja Ossiander ◽

Birgit Weber

Keyword(s):

Schiff Base ◽

High Spin ◽

Spin Crossover ◽

Magnetic Measurements ◽

X Ray ◽

X Ray Crystallography ◽

Tetradentate Schiff Base ◽

Spin Crossover Complexes

A new tetradentate Schiff base-like ligand H2L (1) ((E,E)-dimethyl-2,2´-[1,2-phenylenebis(aminomethylidyne)] bis[3-oxobutanoate]) was synthesised and structurally characterised. Its reaction with iron(II) acetate leads to the formation of the octahedral N2O4-coordinated complex [FeL(MeOH)2] (2). The complex is a pure high-spin (HS) compound as is evident from magnetic measurements and X-ray crystallography.

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