The Effect of Iron Concentration on the High-Spin\(\)Low-Spin Transitions in Iron Compounds

Sorai et al. (Chem. Phys. 18 (1976) 199) observed that the spin transition temperature in [Fe x Zn 1- x (2-pic) 3 ]Cl 2 ·C 2 H 5 OH varies linearly with iron concentration and the slope of the temperature dependence curve of the high-spin content becomes less steep with decreasing concentration. This dilution effect on the high-spin\(\)low-spin transition is studied on the basis of the ligand field theory by taking account of the coupling between d electrons of iron and a lattice strain. The calculated temperature dependence of the high-spin content for various iron concentration reproduces the essential features of the observed results including the linear dependence of the spin transition temperature on the concentration.