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

A water molecule between two complexed MnII centers—that is the salient feature of the title compound 1 (L = dihydroimidazole unit with N[BOND]O and N[BOND]O· 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 MnII model complexes containing O2⊖ and OH⊖ bridges were previously unknown. The d5 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 O2⊖ to OH⊖ to H2O.