Low-temperature lifetimes of metastable high-spin states in spin-crossover and in low-spin iron(II) compounds: The rule and exceptions to the rule

The spin states of the haem components of mixed-valence cytochrome oxidase were studied at room temperature and at temperature down to 20K by using magnetic circular dichroism. The room-temperature studies show the presence of a low-spin ferrous haem together with a low-spin ferric haem, which we attribute to heams a3 and a respectively. At temperatures below 100K it appears that the CO of the mixed-valence CO complex may be irreversibly photolysed, and that in this case haems a and a3 assume their high-spin states. Thus in this enzyme haem-haem interactions appear possible at temperatures below 100K.

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Metal Dilution of Cooperative Spin-Crossover Compounds: When Stable and Metastable High-Spin States Meet

European Journal of Inorganic Chemistry ◽

10.1002/ejic.201201084 ◽

2013 ◽

Vol 2013 (5-6) ◽

pp. 968-974 ◽

Cited By ~ 30

Author(s):

Nicolas Paradis ◽

Guillaume Chastanet ◽

François Varret ◽

Jean-François Létard

Keyword(s):

High Spin ◽

Spin Crossover ◽

Spin States ◽

High Spin States

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New iron(II) spin-crossover complexes with heterocyclic amine-derived ligands and STEPS experiments on photogenerated metastable high-spin states

Journal of the Chemical Society Dalton Transactions ◽

10.1039/dt9870002621 ◽

1987 ◽

pp. 2621 ◽

Cited By ~ 85

Author(s):

Anthony W. Addison ◽

Sudhir Burman ◽

Curtis G. Wahlgren ◽

Odatt A. Rajan ◽

Teresa M. Rowe ◽

...

Keyword(s):

High Spin ◽

Spin Crossover ◽

Spin States ◽

Heterocyclic Amine ◽

High Spin States ◽

Spin Crossover Complexes

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Isoequilibrium relationships and cooperative effects in spin-state transitions in solution

Pure and Applied Chemistry ◽

10.1351/pac200880061281 ◽

2008 ◽

Vol 80 (6) ◽

pp. 1281-1292 ◽

Cited By ~ 14

Author(s):

Nader Hassan ◽

Andrei B. Koudriavtsev ◽

Wolfgang Linert

Keyword(s):

Solid State ◽

High Spin ◽

Molecular Interactions ◽

Thermodynamic Model ◽

Spin Crossover ◽

Statistical Thermodynamic ◽

State Transitions ◽

Spin States ◽

Cooperative Effects ◽

High Spin States

Thermal induced spin transitions between low- and high-spin states of Fe(II) complexes are commonly observed in the solid state. Cooperative effects, such as abrupt and two-step spin crossover, are typical for these objects and arise from intermolecular interactions described by several formalisms. These phenomena appear as deviations from the linearity of the respective van't Hoff plots. In solutions, molecular interactions manifest themselves in isoequilibrium relationships (IERs) as well as in a few cases of specific deviations of van't Hoff plots from linearity. The nature of these phenomena will be discussed on the basis of a statistical-thermodynamic model of spin crossover.

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