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

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.

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Pseudohalogenido complexes of iron-2,2′-bidipyrrins

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424612500538 ◽

2012 ◽

Vol 16 (05n06) ◽

pp. 641-650 ◽

Cited By ~ 14

Author(s):

Martin Bröring ◽

Silke Köhler ◽

Clemens Pietzonka

Keyword(s):

High Spin ◽

Spin State ◽

Elevated Temperatures ◽

High Spin State ◽

Spectroscopic Studies ◽

Axial Ligand ◽

Ligand Field ◽

Central Metal ◽

Exchange Reactions ◽

Dichloromethane Solution

The chlorido iron(III) complex of octaethyl-2,2′-bidipyrrin has been transformed to a series of pseudohalide complexes by ligand exchange reactions with azide, cyanate, thiocyanate and selenocyanate anions. All new complexes show the expected N-coordination of the axial ligand to the iron(III) center. In the solid state, all four species display an intermediate spin (S = 3/2) ground state, with a gradual increase of a high spin (S = 5/2) contribution at elevated temperatures for the members with the smallest ligand field strengths, i.e. the cyanato and the azido derivatives. In solution, proton NMR, and in particular IR spectroscopic studies support the interpretation of a high-spin state at ambient temperature throughout the series. The dependency of the spin state on the crystalline or dissolved state thus resembles that found for a similar series of halide derivatives before. In dichloromethane solution, the thiocyanato and selenocyanato complexes are very sensitive to aerial oxidation, forming oxacorrole and thiacorrole complexes as the only isolated products. These complexes show a S = 3/2 spin state in the solid as well as in solution, and their structural analyses prove the expected strong π-binding of the linear pseudohalide ion to the iron(III) central metal.

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Modeling of Surface and Size Effects on Various Shape of Spin-Crossover Nanoparticles

Materials Science Forum ◽

10.4028/www.scientific.net/msf.793.77 ◽

2014 ◽

Vol 793 ◽

pp. 77-83

Author(s):

Azusa Muraoka ◽

Kamel Boukheddaden

Keyword(s):

High Spin ◽

Spin State ◽

Spin Crossover ◽

Surface Effect ◽

High Spin State ◽

Coordination Shell ◽

Square Lattice ◽

Rectangular Lattice ◽

Ligand Field ◽

Effect Of Surface

We performed of Monte Carlo simulations using Ising-like model on two-dimensional core/shell rectangular lattice L×2L for different sizes in order to study the effect of surface and size on the thermal behavior of spin-crossover nanoparticles. The surface effect is accounted for by constraining all the atoms situated in the boundary in the high-spin state as a result of the weak ligand-field prevailing in the coordination shell. This result is similar to square lattice of spin-crossover nanoparticles, and in agreement with experimental data. Such a non-trivial change is explained as due to the competition between the negative pressures induced the high spin state surface and the bulk properties. We also described the way in which the usual occurrence condition of the first-order transition has to be adapted to the nanoscale.

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

Materials ◽

10.3390/ma13102301 ◽

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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Non-linear Relaxation of the Photo-induced High Spin State in Spin-Crossover Solids: Effect of Correlations

Phase Transitions ◽

10.1080/01411590290033840 ◽

2002 ◽

Vol 75 (7-8) ◽

pp. 733-741 ◽

Cited By ~ 8

Author(s):

K. Boukheddaden ◽

F. Varret ◽

S. Salunke ◽

J. Linares ◽

E. Codjovi

Keyword(s):

High Spin ◽

Spin State ◽

Spin Crossover ◽

High Spin State ◽

Linear Relaxation ◽

Non Linear

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Polymorphism of a chiral iron(ii) complex: spin-crossover and ferroelectric properties

Dalton Transactions ◽

10.1039/c7dt01634d ◽

2017 ◽

Vol 46 (25) ◽

pp. 8004-8008 ◽

Cited By ~ 10

Author(s):

Wang-Kang Han ◽

Long-Fang Qin ◽

Chun-Yan Pang ◽

Cai-Kun Cheng ◽

Wei Zhu ◽

...

Keyword(s):

High Spin ◽

Spin State ◽

Spin Crossover ◽

Ferroelectric Properties ◽

High Spin State ◽

The Other ◽

Complex Spin

A chiral iron(ii) complex with two polymorphs, one that undergoes a gradual spin crossover, whilst the other remains in a high-spin state but shows a typical ferroelectric feature, is reported.

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Steric Trapping of the High Spin State in FeIII Quinolylsalicylaldimine Complexes

Australian Journal of Chemistry ◽

10.1071/ch14177 ◽

2014 ◽

Vol 67 (11) ◽

pp. 1574 ◽

Cited By ~ 4

Author(s):

Darunee Sertphon ◽

David J. Harding ◽

Phimphaka Harding ◽

Keith S. Murray ◽

Boujemaa Moubaraki ◽

...

Keyword(s):

Schiff Base ◽

Electronic Properties ◽

High Spin ◽

Spin State ◽

Schiff Base Ligand ◽

Room Temperature ◽

Spin Crossover ◽

High Spin State ◽

Electrochemical Studies ◽

Magnetic Studies

A new sterically bulky Schiff base ligand, N-(8-quinolyl)-5-tert-butylsalicylaldimine (Hqsal-5-tBu) has been prepared and a series of FeIII complexes, [Fe(qsal-5-tBu)2]Y (Y = Cl 1, ClO4 2, NO3 3, BF4 4) utilising this ligand are reported and fully characterised. UV-vis spectroscopic and electrochemical studies indicate that 1–4 are high spin (HS) in solution at room temperature and further suggest that the tBu group only slightly alters the electronic properties of 1–4 compared with related [Fe(qsal-5-X)2]+ systems. The structures of [Fe(qsal-5-tBu)2]Cl·4MeOH·H2O 1, [Fe(qsal-5-tBu)2]ClO4·MeOH 2, and [Fe(qsal-5-tBu)2]NO3 3 determined at 100 K reveal HS FeIII centres in all cases. Four-fold parallel aryl embraces and π–π interactions serve to link the cations forming 2D sheets mirroring the motifs found in other [Fe(qsal-5-X)2]+ complexes. Despite this the tBu group causes strong distortions at the Fe centre which as magnetic studies reveal prevent spin crossover trapping 1–4 in the HS state.

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The integrated spintronic functionalities of an individual high-spin state spin-crossover molecule between graphene nanoribbon electrodes

Nanotechnology ◽

10.1088/0957-4484/26/31/315201 ◽

2015 ◽

Vol 26 (31) ◽

pp. 315201 ◽

Cited By ~ 16

Author(s):

L Zhu ◽

F Zou ◽

J H Gao ◽

Y S Fu ◽

G Y Gao ◽

...

Keyword(s):

High Spin ◽

Spin State ◽

Spin Crossover ◽

High Spin State ◽

Graphene Nanoribbon ◽

State Spin

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Magnetic fluorescent bifunctional spin-crossover complexes

Dalton Transactions ◽

10.1039/c6dt03714c ◽

2016 ◽

Vol 45 (46) ◽

pp. 18552-18558 ◽

Cited By ~ 21

Author(s):

Jun-Li Wang ◽

Qiang Liu ◽

Xiao-Jin Lv ◽

Rui-Lin Wang ◽

Chun-Ying Duan ◽

...

Keyword(s):

High Spin ◽

Spin State ◽

Spin Crossover ◽

Fluorescence Emission ◽

High Spin State ◽

Spin Crossover Complexes

Bifunctional fluorescent spin crossover complexes exhibit thermally and light induced conversion from the low spin to the high spin state, as well as fluorescence emission.

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