Synthesis,crystal structure and magnetic properties of the spin crossover system [Fe(pq)3]2+ |
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Authors: | Iis Siti Jahro Djulia Onggo Susanto Imam Rahayu M. Carmen Muñoz Ana B. Gaspar Maksym Seredyuk Philipp Gütlich José Antonio Real |
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Affiliation: | 1. Inorganic and Physical Chemistry Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganeca No. 10 Bandung 40132, Indonesia;2. Departament de Física Aplicada, Universitat Politécnica de València, Camino de Vera s/n, 46022 València, Spain;3. Institut de Ciencia Molecular, Universitat de València, Edificios de Institutos de Paterna, P.O. Box 22085, 46071 València, Spain;4. Institut für Anorganische und Analytsische Chemie, Johannes-Gutenberg-Universität, Staudinger-Weg 9, D-55099 Mainz, Germany |
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Abstract: | Three new compounds formulated (ClO4)2[Fe(pq)3] (1), (BF4)2[Fe(pq)3] · EtOH (2) and {(ClO4)[MnCr(C2O4)3][Fe(pq)2(H2O)2]} (3), where pq is 2,2′-pyridylquinoline, have been synthesised and characterised. Despite the different crystal packing exhibited by 1 and 2, the cationic species [Fe(pq)3]2+ are structurally quite similar. At 293 K, the Fe–N bond lengths are characteristic of the iron(II) in the high-spin state. In contrast to 1, 2 undergoes a continuous spin transition. Indeed, at 95 K its structure experiences a noticeable change in the Fe–N bonds and angles, i.e. the Fe–N bonds shorten by 0.194 Å on the average. The magnetic behaviour confirms that 1 is fully high-spin in the 4–300 K temperature range while 2 shows a spin transition centred at T1/2 = 150 K. The corresponding enthalpy, entropy and interaction parameter are ΔH = 7.49 kJ mol?1, ΔS = 50 J K?1 mol?1and Γ = 1.35 kJ mol?1. Compound 3 has been obtained as a microcrystalline powder. The magnetic properties of 3 point at the occurrence of ferromagnetic coupling below 100 K and the onset of a ferromagnetic ordering below 10 K (Weiss constant equal to 6.8 K). The Mössbauer spectra of 3 show the occurrence of a magnetic order at T ? 4.2 K. |
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