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A.B. Koudriavtsev, W. Linert:
"Spin Crossover - A Unique Chemical Equilibrium in the Solid state and its Theoretical Descritpiom";
Hauptvortrag: Xviii Mendeleev Congress On General And Applied Chemistry, Moskau, Russland; 23.09.2007 - 28.09.2007; in: "Xviii Mendeleev Congress On General And Applied Chemistry", (2007), S. 806.

The equilibrium between high-spin and low-spin isomers of Fe(II) and several other metals complexes
(spin crossover) represents a unique test-system for theoretical descriptions of chemical
equilibrium in the solid state. On the other hand the non-trivial behaviour of spin-crossover compounds
makes them promising materials for switching and display devices. Theoretically based synthesis
of spin-crossover compounds requires a molecular theory of the phenomenon. In the present
communication a critical review of various types of spin crossover and theoretical models suggested
for their explanation will be given. The model of many-body interactions and ordering, developed
by the authors1,2, provides for adequate description of all types of spin crossover (including the twostep
spin crossover, Fig. 1) with well-defined and physically transparent estimates of parameters.
The step in the transition curve reflects the formation of ordered structures with alternation of highspin
and low-spin molecules. Parameters controlling the abruptness of transitions and the appearance
of the plateau arise from binary and many-body interactions.

Spin.Crossover, Molecular Magnets