Polymorphism in the spin-crossover ferric complexes [(TPA)Fe(III)(TCC)]PF6
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Updated: Jun 21, 2026

Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyl(tropone)iron
Published on: August 12, 2019
Eric Collet1, Marie Laure Boillot, Johan Hebert
1Institut de Physique de Rennes, UMR-CNRS 6251, Université de Rennes 1 35042 Rennes Cedex, France. eric.collet@univ-rennes1.fr
Abstract:
We have identified two polymorphs of the molecular complex [(TPA)Fe((III))(TCC)]PF(6) [TPA = tris(2-pyridylmethyl)amine and TCC = 3,4,5,6-tetrachlorocatecholate dianion]: one is monoclinic and the other is orthorhombic. By lowering the temperature both undergo a thermal spin-crossover between a high-spin (S = 5/2) and a low-spin (S = 1/2) state, which we detected by magnetic, optical and X-ray diffraction measurements. The thermal crossover is only slightly shifted between the polymorphs. Their crystalline structures consist of similar cation layers alternating with PF(6) anion layers, packed differently in the two polymorphs. The magnetic and optical properties of the polymorphs are presented.
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