Cadmium nitrate coordination polymers with substituted pyridazino[4,5-d] pyridazines

catena-Poly[[aquabis(nitrato-κ²O,O′)cadmium(II)] -μ-1,2,3,6,7,8-hexahydrocinnolino[5,4,3-cde]cinnoline-κN ¹:κN⁶], [Cd(NO₃)₂(C ₁₂H₁₂N₄)(H₂O)]_n, (I), and catena-poly[[[bis(nitrato-κ²O,O′)cadmium(II)]-μ-2,2, 7,7-tetramethyl-1,2,3,6,7,8-hexahydrocinnolino[5,4,3-cde]cinnoline-κN ¹:κN⁶] chloroform solvate], {[Cd(NO ₃)₂(C₁₂H₁₂N₄)] ·CHCl₃}_n, (II), are the first structurally examined cadmium-pyridazine coordination compounds. They possess one-dimensional polymeric structures supported by the bidentate bridging function of the cinnolino[5,4,3-cde]cinnoline ligands, which lie about inversion centres. The Cd atoms are seven-coordinated in (I) and six-coordinated in (II), involving two bidentate nitrate groups [Cd - O = 2.229 (2)-2.657 (2) Å], two N atoms of the cinnoline ligands [Cd - N = 2.252 (2)-2.425 (2) Å], and, additionally, a water O atom in (I) [Cd - O = 2.284 (2) Å]. In (I), the coordinated organic and aqua ligands form an intramolecular O - H⋯N hydrogen bond [O⋯N = 2.730 (3) Å].