Synthesis, Structure and Magnetic Properties of a Dinuclear Manganese( II ) Complex with One μ‐Aqua and Two μ‐Carboxylato Bridges

A water molecule between two complexed Mn II centers —that is the salient feature of the title compound 1 (L = dihydroimidazole unit with NO and NO · functions). A μ‐bridge similar to that in 1 might be present in many natural proteins, for example in the oxygen‐transporting protein hemerythrin. Simple Mn II model complexes containing O 2⊖ and OH ⊖ bridges were previously unknown. The d 5 ions in this series of complexes are antiferromagnetically coupled; the coupling constants decrease by about an order of magnitude for each step on going from O 2⊖ to OH ⊖ to H 2 O.