Evidence for a low temperature phase transition in DI-μ-chloro-tetrakis (ethylene diamine) dinickel(II) chloride

Abstract

The temperature dependence of the heat capacity for the title compound exhibits a broad peak between 10 and 27 K, with a maximum of 35.3 joule mole −1 K −1 at 22.8 K. This heat capacity variation cannot result only from the single-ion zero field splitting and the interaction between Ni(II) ions. It is suggested that a crystallographic phase transition occurs. Low temperature X-ray diffraction diagrams confirm that the compound undergoes a monoclinic → triclinic transition. The consequences of this transition on the interpretation of the magnetic measurements are discussed.