Manganese Oxydiacetate Complexes: Synthesis, Structure and Magnetic Properties

The aerobic aqueous solution syntheses and structures of monomeric and polymeric Mn II complexes containing the oxydiacetate ligand [O(CH 2 COO) 2 2− = oda] are reported. The magnetic properties of the polymeric products have also been investigated. The initially obtained species [{Mn(oda)(H 2 O)}·H 2 O] n ( 1 ) has been reacted with bidentate or tridentate N‐donor ligands such as o ‐phenanthroline (phen), 2,2′‐bipyridine (bipy) and 2,2′:6,2′′‐terpyridine (terpy) to give the complexes [{Mn(oda)(phen)}·4H 2 O] n ( 2 ), [Mn(oda)(bipy)(H 2 O)]·2H 2 O ( 3 ) and [Mn(oda)(terpy)]·2H 2 O ( 4 ), respectively. Species 1 − 4 are the first Mn‐oda structures determined by X‐ray methods. In all cases, the oda acts as a tridentate ligand toward one metal and adopts the typical planar arrangement. However, while the 3 and 4 are monomers, 2 and 1 are polymers as oda exploits both atoms of its carboxylate groups to coordinate other metals; 1 consists of a three‐dimensional diamond‐type network, while 2 is one‐dimensional, consisting of an extended chain of {Mn(oda)(phen)} subunits. For both compounds, magnetic susceptibility measurements down to 2 K showed only weak antiferromagnetic interactions between high‐spin Mn II ions. Despite the expectedly similar coordinating capabilities of N‐donor ligands, the bipy complex 3 is a monomer with the six‐coordination completed by one water ligand. The tridentate nature of simultaneously present oda and terpy ligands excludes the coordination of water in complex 4 , the geometry of which is distorted from the octahedron, most likely due to a peculiar packing effect. Finally, the known five‐coordinate complex [MnCl 2 (terpy)] ( 5 ), a side product of our synthetic experiments, has also been structurally characterized. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)