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): and |
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Authors: | Svetlana G. Baca Helen Stoeckli-Evans Christina Ambrus Stanislav T. Malinovskii Iurii Malaestean Nicolae Gerbeleu Silvio Decurtins |
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Affiliation: | aInstitute of Chemistry, Academy of Sciences of RM, MD-2028 Chisinau, Moldavia;bInstitute of Microtechnology, University of Neuchâtel, CH-2009 Neuchâtel, Switzerland;cDepartment of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland |
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Abstract: | Two new μ3-oxo-centered trinuclear manganese complexes, one of them a homo-valence (1) pivalate complex and the other a mixed-valence (2) 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 1 and 2 are μ3-oxo-trinuclear compounds with the three manganese atoms bridged by six pivalate groups. At each axial position there is an Im (1) or 1-MeIm (2) 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 1 involves hydrogen bonding between complex cations [Mn3O(Piv)6(Im)3]+ and outersphere pivalate ions, whereas in compound 2 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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Keywords: | Manganese complexes Carboxylate complexes Crystal structure Magnetic properties |
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