1,4,5,8-Tetra-methyl-pyridazino[4,5-d]pyridazine trihydrate, C10H12N4·3H2O, (I), and 1,2,3,6,7,8-hexa-hydro-cinnolino[5,4,3-cde] cinnoline tetra-hydrate, C12H12N4·4H2O, (II), exhibit exceptional functionality of the condensed N4-heteroaromatic frame as a symmetric acceptor of four hydrogen bonds [N⋯O = 2.843 (2)-2.8716 (10) Å]. Thus, all the N atoms of the electron-deficient and highly π-acidic polynitro-gen heterocycles function as lone-pair donors. In (I), all the mol-ecular components lie on or across special positions; the site symmetry is 2/m for the organic and m2m and m for the two water mol-ecules. In (II), the organic polycycle lies across a crystallographic inversion center. Both structures involve a hydrogen-bonded centrosymmetric water-pyridazine dimer as the basic supra-molecular unit, which is integrated into two-dimensional [in (I)] and three-dimensional [in (II)] hydrate frameworks by hydrogen bonding with the additional water mol-ecules [O⋯O = 2.744 (2)-2.8827 (19) Å]. The hydrate connectivity exists in the form of an (H2O)3 trimer in (I) and as a one-dimensional zigzag (H2O) n chain in (II).
|Original language||English (US)|
|Journal||Acta Crystallographica Section C: Crystal Structure Communications|
|State||Published - Mar 15 2008|