Exchange-coupled high-spin, low-spin and spin-crossover dicobalt(ii) complexes of a pyridazine-containing Schiff-base macrocycle: control of cobalt(ii) spin state by choice of axial ligands

2002 ◽  
pp. 2080-2087 ◽  
Author(s):  
Sally Brooker ◽  
Duncan J. de Geest ◽  
Robert J. Kelly ◽  
Paul G. Plieger ◽  
Boujemaa Moubaraki ◽  
...  
Keyword(s):  
Schiff Base ◽  
High Spin ◽  
Spin State ◽  
Spin Crossover ◽  
Axial Ligands

Steric Trapping of the High Spin State in FeIII Quinolylsalicylaldimine Complexes

2014 ◽  
Vol 67 (11) ◽  
pp. 1574 ◽  
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.

Spin crossover and high spin electroneutral mononuclear iron(iii) Schiff base complexes involving terminal pseudohalido ligands

2015 ◽  
Vol 39 (1) ◽  
pp. 508-519 ◽  
Author(s):  
Petra Masárová ◽  
Pavel Zoufalý ◽  
Ján Moncol ◽  
Ivan Nemec ◽  
Ján Pavlik ◽  
...  
Keyword(s):  
Schiff Base ◽  
High Spin ◽  
Spin State ◽  
Spin Crossover ◽  
High Spin State ◽  
Schiff Base Complexes ◽  
Mononuclear Iron ◽  
State Behaviour

Six new Schiff-base complexes (1–6) with pseudohalido terminal ligands exhibits spin crossover or high spin state behaviour.

scholarly journals Probing the unpaired Fe spins across the spin crossover of a coordination polymer

2021 ◽  
Author(s):  
Thilini K. Ekanayaka ◽  
Hannah Kurz ◽  
Ashley S. Dale ◽  
Guanhua Hao ◽  
Aaron Mosey ◽  
...  
Keyword(s):  
Schiff Base ◽  
Coordination Polymer ◽  
Spin State ◽  
Spin Crossover ◽  
State Transition ◽  
Spin State Transition

For the spin crossover coordination polymer [Fe(L1)(bipy)]n (where L1 is a N2O22− coordinating Schiff base-like ligand bearing a phenazine fluorophore and bipy = 4,4′-bipyridine), there is compelling additional evidence of a spin state transition.

scholarly journals Temperature dependence of the spin state and geometry in tricobalt paddlewheel complexes with halide axial ligands

2018 ◽  
Vol 47 (46) ◽  
pp. 16798-16806
Author(s):  
Anandi Srinivasan ◽  
Xiaoping Wang ◽  
Rodolphe Clérac ◽  
Mathieu Rouzières ◽  
Larry R. Falvello ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Spin State ◽  
Spin Crossover ◽  
Molecular Geometry ◽  
Axial Ligand ◽  
Paddlewheel Complexes ◽  
Axial Ligands

A series of tricobalt EMACs with halide axial ligands demonstrate diverse spin-crossover behaviors as a function of the molecular geometry and the nature of the axial ligand.

scholarly journals Structural Evidence of Spin State Selection and Spin Crossover Behavior of Tripodal Schiff Base Complexes of tris(2-aminoethyl)amine and Related Tripodal Amines

2020 ◽  
Vol 6 (2) ◽  
pp. 28
Author(s):  
Greg Brewer
Keyword(s):  
Schiff Base ◽  
Spin State ◽  
Density Functional ◽  
Spin Crossover ◽  
Bimodal Distribution ◽  
Structural Features ◽  
Schiff Base Complexes ◽  
Mononuclear Iron ◽  
Experimental Values ◽  
State Selection

A review of the tripodal Schiff base (SB) complexes of tris(2-aminoethyl)amine, Nap(CH2CH 2NH2)3 (tren), and a few closely related tripodal amines with Cr(II), Mn(III) (d4), Mn(II), Fe(III) (d5), Fe(II) (d6), and Co(II) (d7) is provided. Attention is focused on examination of key structural features, the M-Nimine, M-Namine, or M-O and M-Nap bond distances and Nimine-M-N(O) bite and C-Nap-C angles and how these values correlate with spin state selection and spin crossover (SCO) behavior. A comparison of these experimental values with density functional theory calculated values is also given. The greatest number, 132, of complexes is observed with cationic mononuclear iron(II) in a N6 donor set, Fe(II)N6. The dominance of two spin states, high spin (HS) and low spin (LS), in these systems is indicated by the bimodal distribution of histogram plots of Fe(II)-Nimine and Fe(II)-Nazole/pyridine bond distances and of Nimine–Fe(II)-Nazole/pyridine and C-Nap-C bond angles. The values of the two maxima, corresponding to LS and HS states, in each of these histograms agree closely with the theoretical values. The iron(II)-Nimine and iron(II)-Nazole/pyridine bond distances correlate well for these complexes. Examples of SCO complexes of this type are tabulated and a few of the 20 examples are discussed that exhibit interesting features. There are only a few mononuclear iron(III) cationic complexes and one is SCO. In addition, a significant number of supramolecular complexes of these ligands that exhibit SCO, intervalence, and chiral recognition are discussed. A summary is made regarding the current state of this area of research and possible new avenues to explore based on analysis of the present data.

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

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.

scholarly journals Влияние межатомного обменного взаимодействия на магнитные фазовые переходы в условиях спинового кроссовера при высоких давлениях

2018 ◽  
Vol 60 (6) ◽  
pp. 1166
Author(s):  
С.Г. Овчинников ◽  
Ю.С. Орлов ◽  
С.В. Николаев ◽  
А.И. Нестеров ◽  
Т.М. Овчинникова
Keyword(s):  
Experimental Data ◽  
Phase Diagram ◽  
High Spin ◽  
Spin State ◽  
Pressure Dependence ◽  
Spin Crossover ◽  
External Pressure ◽  
Exchange Integral

AbstractThe phase diagram of an antiferromagnet with the spin crossover from the high-spin to low-spin state with S = 0 with increasing external pressure has been calculated with regard to the pressure dependence of the exchange integral. The calculated results are compared with the experimental data on ferropericlase Fe_ x Mg_1 – x O.

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

2002 ◽  
Vol 75 (7-8) ◽  
pp. 733-741 ◽  
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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