| Autor: |
Kizas, C. M., Manos, M. J., Nastopoulos, V., Boudalis, A. K., Sanakis, Y., Tasiopoulos, A. J. |
| Jazyk: |
angličtina |
| Rok vydání: |
2012 |
| Předmět: |
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| Popis: |
Five novel pentanuclear Fe3+ clusters with the aliphatic amino-alcohol ligands 3-amino-1-propanol (Hap) and 2-(hydroxymethyl)piperidine (Hhmpip) [Fe-5(mu(3)-O)(2)(L)(4)(O2CR)(7)] [L = ap(-), R = Ph (1); L = ap(-), R = C(CH3)(3) (2); L = hmpip(-), R = Ph (3); L = hmpip(-), R = C(CH3)(3) (4)] and [Fe-5(mu(4)-O)(mu(3)-O)-(O2CC(CH3)(3))(8)(ap)(2)Cl(HO2CC(CH3)(3))] (5) are reported. Compounds 1-4 were prepared from reactions of preformed trinuclear Fe3+ clusters with the ligands in a molar ratio 1 : 5 in MeCN (1, 3, 4) or DMF (2), whereas compound 5 was prepared from the reaction of FeCl3 with Hap in the presence of HO2CC(CH3)(3) in a molar ratio 1 : 3 : 2 in MeCN. To the best of our knowledge, 1-5 are the first examples of Fe3+ complexes with the ligands Hap and Hhmpip. The structures of 1-4 are composed of a quasi-planar [Fe-5(mu(3)-O)(2)](11+) core which consists of two vertex-sharing [Fe-3(mu(3)-O)](7+) triangles. The structure of 5 is based on the [Fe-5(mu(4)-O)(mu(3)-O)](11+) core, in which the five Fe3+ ions adopt a monocapped trigonal pyramidal topology. Variable-temperature magnetic susceptibility measurements on powdered microcrystalline samples of 1 and 5 revealed the existence of antiferromagnetic interactions which led to an S = 5/2 ground state. Mossbauer spectroscopy studies on powdered microcrystalline samples of 1 and 5 confirmed that all iron ions of both complexes are in the Fe3+ (S = 5/2) state. The variation of the ligand environment in the various iron sites was reflected in their different quadruple splitting parameters. At T < 50 K the Mossbauer spectra indicated the onset of spin relaxation effects in the time scale of the technique (10(-7)-10(-8) s). Dalton Transactions |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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