Iron(II) complexes containing thiophene-substituted “bispicen” ligands — Spin-crossover, ligand rearrangements, and ferromagnetic interactions

2010 ◽  
Vol 88 (9) ◽  
pp. 954-963 ◽  
Author(s):  
Haojin Cheng ◽  
Brandon Djukic ◽  
Hilary A. Jenkins ◽  
Serge I. Gorelsky ◽  
Martin T. Lemaire
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Density Functional Theory Calculations ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Magnetic Analysis ◽  
Ferromagnetic Chain ◽  
Ferromagnetic Interactions

The synthesis and characterization of three new tetradentate “bispicen-type” ligands containing a substituted thiophene heterocycle are described [2,5-thienyl substituents = H (7), Ph (8), or 2-thienyl (9)]. Iron(II) bis(thiocyanate) coordination complexes containing 7–9 were prepared, and the electronic and variable-temperature magnetic properties of complexes containing 7 (10) and 9 (12) are described. Complex 10 features a gradual and incomplete spin crossover in the solid state, and 12 remains high-spin over the entire temperature range. Complex 11 is extremely unstable and rearranges to another iron(II) complex (13), which was structurally characterized. The temperature-dependent magnetic properties of 13 are described as a one-dimensional ferromagnetic chain, with interchain antiferromagnetic interactions and (or) zero-field splitting dominant at low temperatures. The magnetic analysis is corroborated by the molecular packing and density functional theory calculations, which suggest intermolecular interactions between coordinated thiocyanate ligands bearing a significant spin density.

scholarly journals First-Principles Investigations of Magnetic Anisotropy and Spin-Crossover Behavior of Fe(III)-TBP Complexes

2020 ◽  
Author(s):  
Rishu Khurana ◽  
Sameer Gupta ◽  
Md. Ehesan Ali
Keyword(s):  
Single Molecule ◽  
First Principles ◽  
Density Functional ◽  
Spin Crossover ◽  
Zero Field ◽  
Spin States ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
B3lyp Functional ◽  
D Values

<div>With the ongoing efforts to obtain mononuclear 3d-transition metal complexes that manifest slow relaxation of magnetization and hence, can behave as single molecule magnets (SMMs), we have modelled 14 novel Fe(III) complexes out of which nine behave as potential SMMs. These complexes possess large zero-field splitting (ZFS)</div><div>parameter D in the range of -40 to -60 cm<sup>-1</sup>. The first-principles investigation of the ground-spin state applying density functional theory (DFT) and wave-function based</div><div>multi-configurations methods e.g. SA-CASSCF/NEVPT2 are found to be quite consistent except for few delicate cases with near degenerate spin-states. In such cases, the</div><div>hybrid B3LYP functional is found to be biased towards high-spin (HS) state. Altering the percentage of exact exchange admixed in B3LYP functional leads to intermediate spin</div><div>(IS) ground state consistent with the multireference calculations. The origin of large zero field splitting (ZFS) in the Fe(III)-based trigonal bipyramidal (TBP) complexes</div><div>is investigated and the D-values are further tuned by varying the axial ligands with group XV elements (N, P and As) and equatorial halide ligands from F, Cl, Br and I. Furthermore, a number of complexes are identified with very small Gibbs free energy values indicating the possible spin-crossover phenomenon between the bi-stable spin-states.</div>

Crystal structures, magnetic properties, and absorption spectra of nickel(II) thiocyanato complexes: a comparison of different coordination geometries

2003 ◽  
Vol 81 (11) ◽  
pp. 1168-1179 ◽  
Author(s):  
Bruno Larue ◽  
Lan-Tâm Tran ◽  
Dominique Luneau ◽  
Christian Reber
Keyword(s):  
Magnetic Properties ◽  
Crystal Structures ◽  
Absorption Spectra ◽  
Exchange Coupling ◽  
Molecular Magnetism ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Space Group ◽  
Trigonal Bipyramidal ◽  
Ferromagnetic Interactions

Thiocyanatonickel(II) compounds with composition {(AsPh4)2[Ni(NCS)4]} 1, {(Cat)[Ni(NCS)4]} 2, {(AsPh4)4 [Ni2(NCS)8]} 3, {(Cat)2[Ni2(NCS)8]·2CH3NO2} 4, and {(Et4N)4[Ni(NCS)6]} 5 (Cat2+ = (p-xylylenebis(triphenyphosphonium))2+) were prepared. The crystal structures of compounds 1, 3, and 4 were determined. Compound 1 crystallizes in the monoclinic C2/c space group with a = 22.761(2) Å, b = 15.055(1) Å, c = 15.054(1) Å, β = 108.915(1)°, V = 4879.9(6) Å3, and Z = 4. Compound 3 crystallizes in the triclinic P–1 space group with a = 11.2183(6) Å, b = 14.2551(8) Å, c = 16.629(1) Å, α = 79.326(1)°, β = 73.605(1)°, γ = 75.496(1)°, V = 2451.0(2) Å3, Z = 2. Compound 4 crystallizes in the monoclinic P21/n space group with a = 13.1148(9) Å, b = 27.128(2) Å, c = 14.882(1) Å, β = 114.056(2)°, V = 4834.8(6) Å3, Z = 4. The magnetic properties of compounds 1-4 were studied over the 2–300 K temperature range. Compounds 1 and 2 with monometallic [Ni(NCS)4]2– complex units have similar magnetic properties, in agreement with nickel(II) ions in pseudo-tetrahedral environments. Compounds 3 and 4 with bimetallic [Ni2(NCS)8]4– complex units exhibit magnetic properties, which are indicative of Ni(II)–Ni(II) ferromagnetic interactions with zero-field splitting effects caused by the pseudo-square-pyramidal or pseudo-trigonal-bipyramidal coordination environments of the nickel(II) ion in compounds 3 and 4, respectively. The structures and magnetic results for all compounds are correlated with NIR–UV–vis absorption spectra.Key words: nickel(II) thiocyanato complexes, crystal structures, paramagnetism, molecular magnetism, exchange coupling, absorption spectroscopy.

Crystal Structures and Magnetic or Photoluminescent Properties of Copper(II) and Zinc(II)-5-Sulfoisophthalate Coordination Polymers

2010 ◽  
Vol 63 (11) ◽  
pp. 1565 ◽  
Author(s):  
Qing-Yan Liu ◽  
Yu-Ling Wang ◽  
Zi-Yi Du ◽  
Zeng-Mei Shan ◽  
Er-Lei Yang ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Variable Temperature ◽  
Fluorescence Emission ◽  
Zigzag Chain ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Hydrothermal Conditions ◽  
Magnetic Studies ◽  
3D Network ◽  
Ferromagnetic Interactions

{[Cu4(µ3-OH)2(SIP)2(imz)2]·(H2O)2}n (1) and {[Zn3(µ2-OH2)2(SIP)2(phen)3(H2O)3]·(H2O)5}n (2) were obtained under hydrothermal conditions (SIP = 5-sulfoisophthalate, imz = imidazole, and phen = 1,10-phenanthroline). Compound 1 features a novel 3D network based on tetranuclear [Cu4(µ3-OH)2] secondary building unit; its topological structure is similar to that of rutile. Compound 2 is a 1D zigzag chain containing dinuclear [Zn2(µ2-OH2)2(phen)2] and mononuclear [Zn(phen)(H2O)] units. Variable-temperature magnetic studies reveal the existence of dominant ferromagnetic interactions within the tetranuclear copper(ii) cluster in compound 1. Further magnetic measurements indicate that compound 1 has the zero-field splitting parameters D = –0.29 cm–1 and E = 0.00052 cm–1, and g = 2.11 based on ST = 2. Compound 2 exhibits a blue fluorescence emission band at 458 nm on excitation at 391 nm, with a lifetime of 5.78 ns.

scholarly journals First-Principles Investigations of Magnetic Anisotropy and Spin-Crossover Behavior of Fe(III)-TBP Complexes

2020 ◽  
Author(s):  
Rishu Khurana ◽  
Sameer Gupta ◽  
Md. Ehesan Ali
Keyword(s):  
Single Molecule ◽  
First Principles ◽  
Density Functional ◽  
Spin Crossover ◽  
Zero Field ◽  
Spin States ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
B3lyp Functional ◽  
D Values

<div>With the ongoing efforts to obtain mononuclear 3d-transition metal complexes that manifest slow relaxation of magnetization and hence, can behave as single molecule magnets (SMMs), we have modelled 14 novel Fe(III) complexes out of which nine behave as potential SMMs. These complexes possess large zero-field splitting (ZFS)</div><div>parameter D in the range of -40 to -60 cm<sup>-1</sup>. The first-principles investigation of the ground-spin state applying density functional theory (DFT) and wave-function based</div><div>multi-configurations methods e.g. SA-CASSCF/NEVPT2 are found to be quite consistent except for few delicate cases with near degenerate spin-states. In such cases, the</div><div>hybrid B3LYP functional is found to be biased towards high-spin (HS) state. Altering the percentage of exact exchange admixed in B3LYP functional leads to intermediate spin</div><div>(IS) ground state consistent with the multireference calculations. The origin of large zero field splitting (ZFS) in the Fe(III)-based trigonal bipyramidal (TBP) complexes</div><div>is investigated and the D-values are further tuned by varying the axial ligands with group XV elements (N, P and As) and equatorial halide ligands from F, Cl, Br and I. Furthermore, a number of complexes are identified with very small Gibbs free energy values indicating the possible spin-crossover phenomenon between the bi-stable spin-states.</div>

scholarly journals Structural, Electronic, and Magnetic Properties of Mn4N Perovskite: Density Functional Theory Calculations and Monte Carlo Study

2019 ◽  
Vol 33 (5) ◽  
pp. 1507-1512 ◽  
Author(s):  
A. Azouaoui ◽  
M. El Haoua ◽  
S. Salmi ◽  
A. El Grini ◽  
N. Benzakour ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Monte Carlo ◽  
Magnetic Properties ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Generalized Gradient ◽  
Critical Temperatures ◽  
Metallic Behavior ◽  
Functional Theory ◽  
Electronic And Magnetic Properties

AbstractIn this paper, we have studied the structural, electronic, and magnetic properties of the cubic perovskite system Mn4N using the first principles calculations based on density functional theory (DFT) with the generalized gradient approximation (GGA). The obtained data from DFT calculations are used as input data in Monte Carlo simulation with a mixed spin-5/2 and 1 Ising model to calculate the magnetic properties of this compound, such as the total, partial thermal magnetization, and the critical temperatures (TC). The obtained results show that Mn4N has a ferrimagnetic structure with two different sites of Mn in the lattice and presents a metallic behavior. The obtained TC is in good agreement with experimental results.

scholarly journals First principle calculations of electronic and magnetic properties of Mn-doped CdS (zinc blende): a theoretical study

2017 ◽  
Vol 35 (3) ◽  
pp. 479-485 ◽  
Author(s):  
Nisar Ahmed ◽  
Azeem Nabi ◽  
Jawad Nisar ◽  
Muhammad Tariq ◽  
Muhammad Arshad Javid ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Magnetic Moments ◽  
Local Magnetic Moment ◽  
Ferromagnetic Phase ◽  
Generalized Gradient ◽  
Zinc Blende ◽  
Type Semiconductor ◽  
Ferromagnetic Interactions ◽  
Mn Doped

AbstractThe electronic structure and magnetic properties of Mn doped zinc blende cadmium sulfide Cd1-xMnxS (x = 6.25 %) have been studied using spin-polarized density functional theory within the framework of Generalized Gradient Approximation (GGA), its further corrections including Hubbard U interactions (GGA + U) and a model for exchange and correlation potential Tran Blaha modified Becke-Johnson (TB-mBJ). Ferromagnetic interactions have been observed between Mn atoms via S atom due to strong p-d hybridization. The magnetic moments on Mn and its neighboring atoms have also been studied in detail using different charge analysis techniques. It has been observed that p-d hybridization reduced the value of local magnetic moment of Mn in comparison to its free space charge value and produced small local magnetic moments on the nonmagnetic S and Cd host sites. The magnetocrystalline anisotropy in [1 0 0] and [1 1 1] directions as well as exchange splitting parameters Noα and Noβ have been analyzed to confirm that ferromagnetism exists. We conclude that the ferromagnetic phase in Mn-doped CdS is not stable in “near” configuration but it is stable for “far” configuration. Mn doped CdS is a p-type semiconductor and the d-states at the top of the valence band edge give a very useful material for photoluminescence and magneto-optical devices.

Predicting phosphorescent lifetimes and zero-field splitting of organometallic complexes with time-dependent density functional theory including spin–orbit coupling

2014 ◽  
Vol 16 (28) ◽  
pp. 14523-14530 ◽  
Author(s):  
K. Mori ◽  
T. P. M. Goumans ◽  
E. van Lenthe ◽  
F. Wang
Keyword(s):  
Density Functional ◽  
Organometallic Complexes ◽  
Orbit Coupling ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Zero Field Splitting ◽  
Solvation Model ◽  
Functional Theory ◽  
Tddft Calculations

Experimental phosphorescent lifetimes for various organometallic complexes are well reproduced by spin–orbit coupling TDDFT calculations with a continuum solvation model.

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