scholarly journals Magnetic Properties of Fe(II) Complexes of Cyclam Derivative with One p-Aminobenzyl Pendant Arm

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 366
Author(s):  
Bohuslav Drahoš ◽  
Peter Antal ◽  
Ivan Šalitroš ◽  
Radovan Herchel
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
High Spin ◽  
Spin Crossover ◽  
Crystal Packing ◽  
Theoretical Calculations ◽  
High Spin State ◽  
Magnetic Data ◽  
Pendant Arm ◽  
Pendant Arms

In order to prepare an Fe(II) spin crossover (SCO) complex that could be consequently modified to a bimetallic coordination compound that possesses another magnetic property of interest, a specially designed ligand L-NH2 (1-(4-aminobenzyl)-4,11-bis(pyridine-2-ylmethyl)- 1,4,8,11-tetraazacyclotetradecane) was prepared. This ligand consists of a macrocyclic cyclam part containing two 2-pyridylmethyl pendant arms (expecting SCO upon Fe(II) complexation) and one p-aminobenzyl pendant arm with an NH2 group. The presence of this group enables the consequent transformation to various functional groups for the selective complexation of other transition metals or lanthanides (providing the second property of interest). Furthermore, the performed theoretical calculations (TPSSh/def2-TZVP) predicted SCO behavior for the Fe(II) complex of L-NH2. Thus, Fe(II) complexes [Fe(L-NH2)](ClO4)2 (1) and [Fe(L-NH2)]Cl2·6H2O (2) were synthesized and thoroughly characterized. Based on the crystal structure of an isostructural analogous Ni(II) complex [Ni(L-NH2)]Cl2·6H2O (3), the coordination number six was confirmed with an octahedral coordination sphere and a cis-arrangement of the pyridine pendant arms. The measured magnetic data confirmed the high-spin behavior of both compounds with large magnetic anisotropy (D = 17.8 for 1 and 20.9 cm−1 for 2 complemented in both cases also with large rhombicity), though unfortunately without any indication of the SCO behavior with decreasing temperature. The lack of SCO can be ascribed to the crystal packing and/or the non-covalent intermolecular interactions stabilizing the high-spin state in the solid state.

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.

scholarly journals Spin Crossover in Three Mononuclear Iron (III) Schiff Base Complexes

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 849 ◽  
Author(s):  
Ivan Nemec ◽  
Ingrid Svoboda ◽  
Radovan Herchel
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Schiff Base ◽  
Spin Crossover ◽  
Theoretical Calculations ◽  
Magnetic Behavior ◽  
Schiff Base Complexes ◽  
Mononuclear Iron ◽  
Mononuclear Complexes

The synthesis, crystal structure, and magnetic properties of three new mononuclear complexes [Fe(R-LA)(L1)](BPh4), where R-LA2− is a doubly deprotonated pentadentate Schiff base ligand and L1 is a monodentate benzimidazole or furopyridine ligand, are reported. Ligand- and anion-driven changes in crystal structures and magnetic behavior were investigated in terms of the magnetic susceptibility measurements and theoretical calculations.

scholarly journals Steric Quenching of Mn(III) Thermal Spin Crossover: Dilution of Spin Centers in Immobilized Solutions

2022 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Komala Pandurangan ◽  
Anthony B. Carter ◽  
Paulo N. Martinho ◽  
Brendan Gildea ◽  
Tibebe Lemma ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Structural Analysis ◽  
High Spin ◽  
Spin State ◽  
Spin Crossover ◽  
High Spin State ◽  
Spectroscopic Studies ◽  
Raman Spectroscopic ◽  
Spin Triplet ◽  
Structural And Magnetic Properties

Structural and magnetic properties of a new spin crossover complex [Mn(4,6-diOMe-sal2323)]+ in lattices with ClO4−, (1), NO3−, (2), BF4−, (3), CF3SO3−, (4), and Cl− (5) counterions are reported. Comparison with the magnetostructural properties of the C6, C12, C18 and C22 alkylated analogues of the ClO4− salt of [Mn(4,6-diOMe-sal2323)]+ demonstrates that alkylation effectively switches off the thermal spin crossover pathway and the amphiphilic complexes are all high spin. The spin crossover quenching in the amphiphiles is further probed by magnetic, structural and Raman spectroscopic studies of the PF6− salts of the C6, C12 and C18 complexes of a related complex [Mn(3-OMe-sal2323)]+ which confirm a preference for the high spin state in all cases. Structural analysis is used to rationalize the choice of the spin quintet form in the seven amphiphilic complexes and to highlight the non-accessibility of the smaller spin triplet form of the ion more generally in dilute environments. We suggest that lattice pressure is a requirement to stabilize the spin triplet form of Mn3+ as the low spin form is not known to exist in solution.

High-spin tetranuclear iron(III) grids: Synthesis, crystal structure and magnetic properties

Polyhedron ◽  
2013 ◽  
Vol 52 ◽  
pp. 970-975 ◽  
Author(s):  
Yi-Tong Wang ◽  
Ai-Li Cui ◽  
De-Zhong Shen ◽  
Hui-Zhong Kou
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
High Spin

scholarly journals Spin Cross-Over (SCO) Complex Based on Unsymmetrical Functionalized Triazacyclononane Ligand: Structural Characterization and Magnetic Properties

2019 ◽  
Vol 5 (1) ◽  
pp. 19 ◽  
Author(s):  
Merzouk Halit ◽  
Mélissa Roger ◽  
Véronique Patinec ◽  
Said Yefsah ◽  
Carlos Gómez-García ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Magnetic Properties ◽  
Nmr Spectroscopy ◽  
Functional Groups ◽  
Structural Characterization ◽  
Spin Crossover ◽  
Magnetic Studies ◽  
Dsc Measurements ◽  
Hexadentate Ligand

The unsymmetrical ligand 1-(2-aminophenyl)-4,7-bis(pyridin-2-ylmethyl)-1,4,7-triazacyclononane (L6) has been prepared and characterized by NMR spectroscopy. The L6 ligand is based on the triazamacrocycle (tacn) ring that is functionalized by two flexible 2-pyridylmethyl and one rigid 2-aminophenyl groups. Reaction of this ligand with Fe(ClO4)2·xH2O led to the complex [Fe(L6)](ClO4)2 (1), which was characterized as the first Fe(II) complex based on the unsymmetrical N-functionalized tacn ligand. The crystal structure revealed a discrete monomeric [FeL6]2+ entity in which the unsymmetrical N-functionalized triazacyclononane molecule (L6) acts as hexadentate ligand. As observed in the few parent examples that are based on the symmetrical N-functionalized tacn ligands, the triazacyclononane ring is facially coordinated and the N-donor atoms of the three functional groups (two pyridine and one aniline groups) are disposed in the same side of the tacn ring, leading to a distorted FeN6 environment. The magnetic studies of 1 revealed the presence of an incomplete spin crossover (SCO) transition above 425 K, whose progress would be prevented by a very exothermic thermal decomposition at ca. 472 K, as shown by thermogravimetric and DSC measurements.

scholarly journals Crystal structure of bis(azido-κN)bis(quinolin-8-amine-κ2N,N′)iron(II)

2016 ◽  
Vol 72 (10) ◽  
pp. 1488-1491
Author(s):  
Fatima Setifi ◽  
Dohyun Moon ◽  
Robeyns Koen ◽  
Zouaoui Setifi ◽  
Morad Lamsayah ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Structure Determination ◽  
Crystal Packing ◽  
Octahedral Geometry ◽  
Title Complex ◽  
Two Dimensional ◽  
Azide Ion ◽  
Amine Ligands

The search for new molecular materials with interesting magnetic properties using the pseudohalide azide ion and quinolin-8-amine (aqin, C9H8N2) as a chelating ligand, led to the synthesis and structure determination of the title complex, [Fe(N3)2(C9H8N2)2]. The complex shows an octahedral geometry, with the FeIIatom surrounded by six N atoms; the two N3−anions coordinate in acisconfiguration, while the remaining N atoms originate from the two quinolin-8-amine ligands with the quinoline N atoms lying on opposite sides of the Fe atom. The crystal packing is dominated by layers of hydrophilic and aromatic regions parallel to theacplane, stabilized by a two-dimensional hydrogen-bonded network and π–π stacking.

Crystal Structure and Magnetic Properties of the Novel Hollandite Ba1.3Co1.3Ti6.7O16

2011 ◽  
Vol 66 (11) ◽  
pp. 1097-1100 ◽  
Author(s):  
Larysa Shlyk ◽  
Rainer Niewa
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Single Crystals ◽  
Magnetic Moment ◽  
High Spin State ◽  
The Novel ◽  
Charge Balance ◽  
Vertex Sharing ◽  
State Spin

Single crystals of the new barium hollandite Ba1.3Co1.3Ti6.7O16 were obtained from a BaCl2 flux (I2/m, Z = 1, a = 9.9470(4), b = 2.9714(2), c = 10.2260(5) Å , β = 90.906(2)◦). In the crystal structure piles of Ba atoms are situated within a framework of edge- and vertex-sharing octahedra (Co,Ti)O6. The composition was deduced from microprobe analyses, structure refinements and charge balance arguments in agreement with the observed magnetic properties. The temperature dependence of the magnetic susceptibility χ(T) of Ba1.3Co1.3Ti6.7O16 single crystals reveals paramagnetism down to 2 K. The value of the Co magnetic moment deduced from the Curie-Weiss law agrees well with the theoretical value of the high-spin state spin-only moment of μeff = 3.87 μB for Co2+ (S = 3/2)

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