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Synthesis, crystal structures and magnetic properties of trinuclear oxo-centered homo- and mixed-valence manganese pivalate complexes with imidazole (Im) and 1-methylimidazole (1-MeIm): [Mn<sub>3</sub><sup>III</sup>0(0<sub>2</sub>CCMe<sub>3</sub>)<sub>6</sub> (Im)<sub>3</sub>](Me<sub>3</sub>CC0<sub>2</sub>)•0.5Me<sub>3</sub>CC0<sub>2</sub>H and [Mn<sub>2</sub><sup>III</sup>Mn<sup>II</sup>0(0<sub>2</sub>CCMe<sub>3</sub>)<sub>6</sub>(1-MeIm)<sub>3</sub>]
Auteur(s)
Baca, Svetlana G.
Ambrus, Christina
Malinovskii, Stanislav T.
Malaestean, Iurii
Gerbeleu, Nicolae
Decurtins, Silvio
Date de parution
2006
In
Polyhedron, Elsevier, 2006/25/18/3617-3627
Résumé
Two new μ<sub>3</sub>-oxo-centered trinuclear manganese complexes, one of them a homo-valence [Mn<sub>3</sub><sup>III</sup>0(0<sub>2</sub>CCMe<sub>3</sub>)<sub>6</sub> (Im)<sub>3</sub>](Me<sub>3</sub>CC0<sub>2</sub>)•0.5Me<sub>3</sub>CC0<sub>2</sub>H (<b>1</b>) pivalate complex and the other a mixed-valence [Mn<sub>2</sub><sup>III</sup>Mn<sup>II</sup>0(0<sub>2</sub>CCMe<sub>3</sub>)<sub>6</sub>(1-MeIm)<sub>3</sub>] (<b>2</b>) pivalate complex (where Im = imidazole, 1-MeIm = 1-methylimidazole), have been synthesized and characterized by IR spectroscopy, thermogravimetric analysis, X-ray crystallography and magnetochemistry. Complexes <b>1</b> and <b>2</b> are μ3-oxo-trinuclear compounds with the three manganese atoms bridged by six pivalate groups. At each axial position there is an Im (<b>1</b>) or 1-MeIm (<b>2</b>) molecule. In both compounds, the manganese coordination geometry is slightly distorted octahedral, consisting of the oxygen of the central triangle, four oxygen atoms from bridging pivalate ligands, and a terminal Im or 1-MeIm nitrogen atom. The crystal packing of <b>1</b> involves hydrogen bonding between complex cations [Mn<sub>3</sub>O(Piv)<sub>6</sub>(Im)<sub>3</sub>]<sup>+</sup> and outersphere pivalate ions, whereas in compound <b>2</b> interactions of the C–Hπ type, formed by both the aromatic and methyl C–H groups of 1-MeIm molecules, are present. Magnetic studies reveal that both compounds represent antiferromagnetically coupled, spin-frustrated triangular systems exhibiting weak to moderate exchange coupling constants.
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Type de publication
journal article
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