Bioanorganische Modellkomplexe für Metalloproteine des Eisen(III) und Mangan(III): Synthese, Magnetismus und Kristallstrukturen von [L2Fe2(acac)2(μ-O)](ClO4)2, [L'Mn(acac)(OC2H5)]BPh4 und [L'Mn(acac)(OH2)](ClO4)2 (L = 1,4,7-Triazacyclononan, L' = N,N',N"-Trimethyl-1,4,7-triazacyclononan)
Open Access
- 1 September 1988
- journal article
- Published by Walter de Gruyter GmbH in Zeitschrift für Naturforschung B
- Vol. 43 (9) , 1184-1194
- https://doi.org/10.1515/znb-1988-0917
Abstract
The reaction of Fe(acac)3 (acac = acetylacetonate, 2,4-pentanedionate) with 1,4,7-triazacyclo- nonane (L) in acetone in the presence of water and NaClO4 yields green crystals of [L2Fe2 III(acac)2(μ-O)](ClO4)2 (1) a μ-oxo bridged dimer of Fe(III) the crystal structure of which has been determined. Hydrolysis of this material in an acetone/water mixture in the presence of NaBr yields the green tetramer [L4Fe4 III(μ-O)2(μ-OH)4]Br4 · 4H2O. Both compounds are strongly intramolecularly antiferromagnetically coupled. In contrast, the analogous reaction of Mn(acac)3 with L or N,N',N"-trimethyl-1,4,7-triazacyclononane (L') in ethanol or methanol yields yellow- green monomeric complexes of the type [LMnIII(acac)(OR)]+ or [L'Mn(acac)(OR)]+ (R = CH3, C2H5) which were isolated as tetraphenylborate or hexafluorophosphate salts. The crystal structure of [L'Mn(acac)(OC2H5)]BPh4 (2) has been determined. If to the above reaction mixture cone. HClO4 was added, red [L'Mn(acac)(H2O)](CLO4)2 (3) precipitated. In alkaline aqueous solution [L'Mn(acac)(OH)]+ prevails. The crystal structure of 3 has also been determined. The new monomeric manganese(III) complexes have temperature independent (100-300 K) magnetic moments of 4.8 to 5.1 μB in agreement with a high spin (d4) electronic configuration.Keywords
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