Acta Crystallographica Section B

Structural Science

Volume 65, Part 4 (August 2009)

research papers

Acta Cryst. (2009). B65, 474-480 [ doi:10.1107/S0108768109021508 ]

Polymorphism in the spin-crossover ferric complexes [(TPA)Fe^III(TCC)]PF₆

E. Collet, M.-L. Boillot, J. Hebert, N. Moisan, M. Servol, M. Lorenc, L. Toupet, M. Buron-Le Cointe, A. Tissot and J. Sainton

Abstract: We have identified two polymorphs of the molecular complex [(TPA)Fe^(III)(TCC)]PF₆ [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 PF₆ anion layers, packed differently in the two polymorphs. The magnetic and optical properties of the polymorphs are presented.

Keywords: spin-crossover; polymorphism; phase transition.


	Structure factor file (CIF format) (182.8 kbytes) [ doi:10.1107/S0108768109021508/og5037mono80sup2.fcf ] Contains datablock mono80

	Structure factor file (CIF format) (100.4 kbytes) [ doi:10.1107/S0108768109021508/og5037ortho80sup3.fcf ] Contains datablock ortho80

	Structure factor file (CIF format) (177.0 kbytes) [ doi:10.1107/S0108768109021508/og5037mono400sup4.fcf ] Contains datablock mono400

	Structure factor file (CIF format) (104.7 kbytes) [ doi:10.1107/S0108768109021508/og5037ortho400sup5.fcf ] Contains datablock ortho400

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