Structure and spin crossover in an iron(II) compound with tris(pyrazol-1-yl)methane and the complex Eu(dipic)2(Hdipic)]2– anion

Abstract

An iron(II) complex with tris(pyrazol-1-yl)methane (HC(Pz)₃) of the composition [Fe(HC(Pz)₃))₂]·[Eu(dipic)₂(Hdipic)]·2H₂O, containing an outer-sphere complex anion, is synthesized. The compound is examined by single crystal and powder X-ray diffraction, UV-Vis and IR spectroscopies, and static magnetic susceptibility. The investigation of the temperature dependence χ(T) in the temperature range 80-470 K reveals that the polycrystalline phase of the compound undergoes spin-crossover ¹А₁ ⇔ ⁵Т₂. The transition is accompanied by thermochromism (color change pink ⇔ white).