Electronic Structures of Tetragonal Sixfold-Coordinated Iron (III) Complexes with High-Spin—Intermediate-Spin Transitions

1995 ◽  
Vol 191 (2) ◽  
pp. 395-400 ◽  
Author(s):  
Xiao-Yu Kuang ◽  
Irène Morgenstern-Badarau
Keyword(s):  
High Spin ◽  
Electronic Structures ◽  
Intermediate Spin ◽  
Spin Transitions

MO-Theoretical Studies on a Model Complex for Deoxymyoglobin

1998 ◽  
Vol 53 (9) ◽  
pp. 755-765
Author(s):  
Christian Kollma ◽  
Sighart F. Fischer ◽  
Michael C. Böhm
Keyword(s):  
High Spin ◽  
Ground State ◽  
High Spin State ◽  
Open Shell ◽  
Spin States ◽  
Hartree Fock ◽  
Intermediate Spin ◽  
Model Complex ◽  
Out Of Plane ◽  
Overlap Method

AbstractThe origin of the displacement of the Fe atom in deoxymyoglobin with respect to the porphyrin plane in the high-spin state is examined by a qualitative molecular orbital (MO) analysis on the extended Hückel level. We find that attachment of a fifth ligand (imidazole in our model complex) to Fe(II)porphyrin favors the out-of-plane shift due to a strengthening of the bonding interaction between Fe and the nitrogen of the imidazole ligand. This results in a high-spin (5 = 2) ground state with Fe shifted out-of-plane for the five-coordinate complex instead of an intermediate spin ground state (5 = 1) with Fe lying in the plane for four-coordinate Fe(II)porphyrin. The relative energies of the different spin states as a function of the distance between Fe and the porphyrin plane are evaluated using an ROHF (restricted open shell Hartree-Fock) version of an INDO (intermediate neglect of differential overlap) method. We observe a level crossing between high-spin and intermediate spin states whereas the low-spin (5 = 0) state remains always higher in energy.

The effect of the lattice expansion on high spin ⇌ low spin transitions

1982 ◽  
Vol 68 (1-2) ◽  
pp. 65-71 ◽  
Author(s):  
H. Spiering ◽  
E. Meissner ◽  
H. Köppen ◽  
E.W. Müller ◽  
P. Gütlich
Keyword(s):  
High Spin ◽  
Lattice Expansion ◽  
Spin Transitions

Solute-Solvent Interactions and High Spin ⇌ Low Spin Transitions in Ferric Dithiocarbamates

1985 ◽  
Vol 40 (1) ◽  
pp. 79-83
Author(s):  
P. Ganguli
Keyword(s):  
High Spin ◽  
Alkyl Chain ◽  
Preferential Solvation ◽  
Solvent Interactions ◽  
Spin Transitions

The HS ⇌ LS transition in ferric dithiocarbamates in a number of solvents has been investigated using NMR and is interpreted in terms of preferential solvation or second co-ordination sphere reorganisation effects. These studies clearly demonstrate that neglect of pseudo contact shifts can lead to erroneous conclusions about the spin delocalisation mechanisms. The spin derealization in these systems is by direct σ-delocalization along the alkyl chain. The As values of 2T2 and 6A1 states have the same sign.

scholarly journals Adsorption of iron tetraphenylporphyrin on (111) surfaces of coinage metals: a density functional theory study

2017 ◽  
Vol 8 ◽  
pp. 2484-2491 ◽  
Author(s):  
Hao Tang ◽  
Nathalie Tarrat ◽  
Véronique Langlais ◽  
Yongfeng Wang
Keyword(s):  
Density Functional Theory ◽  
High Spin ◽  
Density Functional ◽  
Activation Barrier ◽  
High Spin State ◽  
Coulomb Repulsion ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Intermediate Spin ◽  
Magnetic States

The adsorption of the iron tetraphenylporphyrin (FeTPP) molecule in its deckchair conformation was investigated on Au(111), Ag(111) and Cu(111) surfaces by performing spin-polarized density functional theory (DFT) calculations taking into account both van der Waals (vdW) interaction and on-site Coulomb repulsion. The deckchair conformation of the molecule favours intermolecular π–π-type interactions in a less densely packed monolayer than the saddle conformation. The activation barrier between the two stable magnetic states (high spin, S = 2 and intermediate spin, S = 1) of the molecule in vacuum disappears upon adsorption on the metal surfaces. The high-spin state of physisorbed FeTPP is stable on all adsorption sites. This result reveals that an external permanent element such as a STM tip or an additional molecule is needed to use FeTPP or similar molecules as model system for molecular spin switches.

Coupling of Lattice Dynamics to Spin Transitions in La1-xSrxCoO3

2002 ◽  
Vol 718 ◽  
Author(s):  
Despina Louca ◽  
J. L. Sarrao
Keyword(s):  
Function Analysis ◽  
Dynamic Structure ◽  
Spin Configuration ◽  
Spin Lattice ◽  
Intermediate Spin ◽  
Pair Density ◽  
Variable Spin ◽  
Local Lattice ◽  
Jahn Teller ◽  
Spin Transitions

AbstractLa1-xSrxCoO3 is distinct because of its unique spin transitions subjecting the system to variable spin-lattice coupling. Pair density function analysis provided strong evidence for local lattice distortions associated with a Jahn-Teller active mode that is directly correlated to the change in the magnetic/conductive states of this system. The presence of Jahn-Teller distortions also serves as an indication for the intermediate spin configuration. Measurements of the dynamic structure function, S(Q, ω), showed that several phonon peaks fluctuate with carrier density and temperature. Such changes were not seen in an otherwise identical structure, LaAlO3. These phonon peaks are quite unusual and are most likely due to localized modes that appear to be dispersionless.

Temperature-dependent magnetic moments of Fe(III) complexes with high-spin–low-spin transitions

1993 ◽  
Vol 47 (9) ◽  
pp. 5455-5458 ◽  
Author(s):  
Kuang Xiao-Yu ◽  
Irène Morgenstern-Badarau ◽  
Isabelle Malfant
Keyword(s):  
High Spin ◽  
Magnetic Moments ◽  
Temperature Dependent ◽  
Spin Transitions

scholarly journals Computational Design of Mn4 Molecules with Strong Intramolecular Exchange Coupling

2011 ◽  
Vol 21 (2) ◽  
pp. 137
Author(s):  
Nguyen Anh Tuan ◽  
Nguyen Van Thanh ◽  
Tran Thi Thuy Nu ◽  
Nguyen Huy Sinh ◽  
Vu Van Khai ◽  
...  
Keyword(s):  
High Spin ◽  
Single Molecule ◽  
First Principles ◽  
Electronic Structures ◽  
Exchange Coupling ◽  
Computational Design ◽  
First Principles Calculations ◽  
Single Molecule Magnets ◽  
Intramolecular Exchange ◽  
Ferrimagnetic Structure

The geometric and electronic structures of [Mn44+Mn3+3(µ3-L2 -)3(µ3-X -(OAc) - 3(dbm) -3] (L = O, X = F, dbmH = dibenzoyl-methane) molecule has been studied by first-principles calculations. It was shown in our previous paper that the ferrimagnetic structure of Mn$^{4 + }$Mn$^{3 + }_{3}$ molecules is determined by the $\pi $ type hybridization between the $d_{z^2}$ orbitals at the three high-spin Mn$^{3 + }$ ions and the $t_{2g}$ orbitals at the Mn$^{4 + }$ ion by the $p$ orbitals at the $\mu _{3}$-L$^{2 - }$ ions. To design new Mn$^{4 + }$Mn$^{3 + }_{3}$ molecules having much more stable ferrimagnetic state, one approach is suggested. That is controlling the Mn$^{4 + }$-($\mu _{3}$-L$^{2 - })$-Mn$^{3 + }$ exchange pathways by rational variation in $\mu _{3}$-L ligands to strengthen the hybridization between Mn ions. By this ligand variation, $J_{AB}$ can be enhanced by a factor of 3. Our results should facilitate the rational synthesis of new single-molecule magnets.

scholarly journals Co-Substitution Effect in Room-Temperature Ferromagnetic Oxide Sr3.1Y0.9Co4O10.5

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2301
Author(s):  
Akihiro Tsuruta ◽  
Shuji Kawasaki ◽  
Masashi Mikami ◽  
Yoshiaki Kinemuchi ◽  
Yoshitake Masuda ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
High Spin ◽  
Spin State ◽  
Room Temperature ◽  
High Spin State ◽  
Substitution Effect ◽  
Co Substitution ◽  
Intermediate Spin ◽  
Intermediate Spin State

We investigated the Co substitution effect for the magnetic properties in room-temperature ferromagnetic oxide Sr3.1Y0.9Co4O10.5. The substituted element (Al and Ga) and low-spin state Co3+, which was changed from a high-spin or intermediate-spin state by Al or Ga substitution, reduced the Curie temperature to even 1.5 times lower than the temperature estimated from a simple dilution effect. Al3+ preferentially substituted for intermediate-spin-state Co3+ in the ferrimagnetic CoO6 layer and deteriorated the saturation magnetization of Sr3.1Y0.9Co4O10.5. By contrast, Ga3+ substituted for high-spin-state Co3+ in the CoO6 layer and/or the antiferromagnetic CoO4.25 layer and enhanced the saturation magnetization per Co ion. These results indicate that the magnetic properties of Sr3.1Y0.9Co4O10.5 can be controlled by selectively substituting for Co3+ with different spin states.

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