Metal Binding of Polyalcohols. 4. Structure and Magnetism of the Hexanuclear, μ6-Oxo-Centered [OFe6(H-3thme)3(OCH3)3Cl6]2- (thme = 1,1,1-Tris(hydroxymethyl)ethane)
- 1 January 1996
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 35 (15) , 4414-4419
- https://doi.org/10.1021/ic960025s
Abstract
The addition of [N(CH3)4]OH to a methanolic solution of FeCl3 and thme (thme = 1,1,1-tris(hydroxymethyl)ethane) yielded [N(CH3)4]2[OFe6(H-3thme)3(OCH3)3Cl6]·2H2O (1). Crystal data: C26H64Cl6Fe6N2O15, trigonal space group P31c, a = 12.459(2) Å, c = 18.077(4) Å, Z = 2. The complex anion exhibits the well-known μ6-O−Fe6−(μ2-OR)12 structure with three μ2-methoxo bridges, three triply deprotonated H-3thme ligands, where each alkoxo group bridges two FeIII centers, and six terminally coordinating Cl- ligands. In contrast to two previously described ferric complexes with an analogous structure of the complex core, compound 1 is stable in air. Variable-temperature magnetic susceptibility measurements established antiferromagnetic exchange coupling interactions with Jtrans(Fe−μ6-O−Fe) = 24.5 cm-1, Jcis(Fe−μ2-Othme−Fe) = 11.5 cm-1, and Jcis‘(Fe−μ2-OCH3−Fe) = 19.5 cm-1. The unexpectedly high value for Jtrans is explained by means of a superexchange pathway and is discussed for a simplified model by using MO calculations at the extended Hückel level.Keywords
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