Diaquabis(pyridazin-1-ium-3,6-dicarboxyl-ato-N-2,O-3)copper(II) dihydrate

The crystal structure of the title compound, [Cu(C6H3-N2O4)(2)(H2O)(2)]. 2H (2)O, shows it to exist as a monometalic and centrosymmetric complex with o ctahedral coordination of copper to each of two pyridazinium-3,6-dicarboxyl ate groups lying in the equatorial plane via one N and one O atom, and to t wo water molecules in trans-diaxial positions. Two additional water molecul es are included in the cell. A network of hydrogen bonding links the carbox yl groups and the water molecules of the cell.