66182-88-5Relevant academic research and scientific papers
Solid-phase thermal square-planar-to-octahedral isomeric transformation of nickel(II) complexes containing 1,2-cyclohexanediamines
Ihara, Yoshinori,Fukuda, Yutaka,Sone, Kozo
, p. 3745 - 3750 (2008/10/08)
New examples of thermal square-planar (low-spin)-to-octahedral (high-spin) isomeric transformations were discovered and studied in the thermal reactions of bis(dl- or meso-1,2-cyclohexanediamine)nickel(II) complexes, [Ni(dl- or ms-chxn)2]X2 (X = Cl, Br, NO3), in the solid phase. These transformations proceeded endothermically and were accompanied by a reversible thermochromism from yellow to violet-blue. Obvious differences in the reactivity between the ms-chxn complexes and the ms-chxn ones were observed. They indicate that this type of reaction (and the stability of the square-planar species) is strongly dominated by the steric effect of the substituent groups in the coordinated diamines. The enthalpy changes for these endothermic transformations were found to be small (8 kJ/mol). The activation energies for them were also estimated.
