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Cornia A, Gatteschi D, Hegetschweiler K, Hausherr-Primo L, Gramlich V: Metal Binding of Polyalcohols. 4. Inorg Chem. 1996 Jul 17;35(15):4414-4419.
Structure and Magnetism of the Hexanuclear, &mgr;(6)-Oxo-Centered [OFe (6)(H (-)(3) thme)(3)(OCH (3))(3) Cl (6)](2)(-) (thme = 1,1,1-Tris (hydroxymethyl) ethane).. The addition of [N (CH (3))(4)] OH to a methanolic solution of FeCl (3) and thme (thme = 1,1,1-tris (hydroxymethyl) ethane) yielded [N (CH (3))(4)](2)[OFe (6)(H (-)(3) thme)(3)(OCH (3))(3) Cl (6)].2H (2) O (1). Crystal data: C (26) H (64) Cl (6) Fe (6) N (2) O (15), trigonal space group P31c, a = 12.459 (2) A, c = 18.077 (4) A, Z = 2. The complex anion exhibits the well-known &mgr;(6)-O-Fe (6)-(&mgr;(2)-OR)(12) structure with three &mgr;(2)-methoxo bridges, three triply deprotonated H (-)(3) thme ligands, where each alkoxo group bridges two Fe (III) 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 J (trans)(Fe-&mgr;(6)-O-Fe) = 24.5 cm (-)(1), J (cis)(Fe-&mgr;(2)-O (thme)-Fe) = 11.5 cm (-)(1), and J (cis)'(Fe-&mgr;(2)-OCH (3)-Fe) = 19.5 cm (-)(1). The unexpectedly high value for J (trans) is explained by means of a superexchange pathway and is discussed for a simplified model by using MO calculations at the extended Huckel level. |
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