title: Polymorphism in the spin-crossover ferric complexes [(TPA)Fe(III)(TCC)]PF6.
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.
authors.affiliation: Institut de Physique de Rennes, UMR-CNRS 6251, Université de Rennes 1 35042 Rennes Cedex, France. eric.collet@univ-rennes1.fr
authors.forename: Eric
authors.initials: E
authors.lastname: Collet
authors.forename: Marie Laure
authors.initials: ML
authors.lastname: Boillot
authors.forename: Johan
authors.initials: J
authors.lastname: Hebert
authors.forename: Nicolas
authors.initials: N
authors.lastname: Moisan
authors.forename: Marina
authors.initials: M
authors.lastname: Servol
authors.forename: Maciej
authors.initials: M
authors.lastname: Lorenc
authors.forename: Loïc
authors.initials: L
authors.lastname: Toupet
authors.forename: Marylise
authors.initials: M
authors.lastname: Buron-Le Cointe
authors.forename: Antoine
authors.initials: A
authors.lastname: Tissot
authors.forename: Joelle
authors.initials: J
authors.lastname: Sainton