Spin-Crossover Phenomena of Ni(cyclam)I2 Complex: Magnetostructural Correlations in Two Polymorphs

Two crystal polymorphs of Ni(cyclam)I2 (cyclam = 1,4,8,11-
tetraazacyclotetradecane) were identified by X-ray structural analysis and their magnetic properties were investigated. Gradual spin-crossover behaviors were found in both polymorphs. Entropy differences between high- and low-spin states obtained by assuming the spin equilibrium model reflected subtle difference of the coordination environment of nickel(II) ion in two polymorphs.