M. Devereux, M. Mccann, V. León
May 15, 2002
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Journal
Polyhedron
Abstract
Abstract Reactions of manganese(II) acetate with 2-pyrazine carboxylic acid, 2,6-pyridinedicarboxylic acid and chelidamic acid (4-hydroxypyridine-2,6-dicarboxylic acid) yielded [Mn(pyr)2]n (1), [Mn(dipic)]·1.5H2O (2) and Mn(chedam)]·H2O (6), respectively. Reaction of 2 with 2,2′-bipyridine and 1,10-phenanthroline results in the synthesis of [Mn(dipic)(bipy)]·2H2O (3), [Mn(dipic)(bipy)2]·4.5H2O (4) and [Mn(dipic)(phen)2]·2H2O (5). Complex 6 reacted with 2,2′-bipyridine and 1,10-phenanthroline to give [Mn(chedam)(bipy)]·H2O (7) and [Mn(chedam)(phen)2]·3H2O (8), respectively. Molecular structures for 1, 4 and 7 were determined by X-ray crystallography. In 1 the structure is essentially polymeric with each pyrazine carboxylate anion coordinated to the manganese ion in a bidentate fashion using one carboxylate oxygen atom and the adjacent nitrogen. The second nitrogen is uncoordinated. For 4 the asymmetric unit consists of one tridentate dipicolinate ligand, two bidentate bipyridine molecules, four full-occupancy water molecules and one half-occupancy water molecule. The structure of 7 contains monomeric [Mn(dicarboxylate)(bipy)H2O] units in which the Mn(II) ions have very irregular six-coordinate geometry. Spectroscopic, magnetic and physical data for the complexes are presented. All of the manganese complexes catalytically disproportionate hydrogen peroxide in the presence of imidazole.