2,8-Dihydroxy-1,3,7,9-tetramethyl-6,12-dihydrodipyrido

The 2,8-dihydroxy-1,3,7,9-tetramethyl-6,12-dihydrodipyrido[1,2-a:1', 2'-d]pyrazinediylium dication possesses 2/m symmetry and lies in the mirror plane together with a chloride anion and the water O atom. The dication also lies on an inversion centre, i.e. C(16)H(20)N(2)O(2)(2+).2Cl(-).2H(2)O. Due to these symmetry constrictions the dication adopts an unexpected planar conformation. Molecules are linked by O-H.O and O-H.Cl hydrogen bonds to form chains, which are cross-connected by C-H.Cl attractive interactions forming a complex three-dimensional hydrogen-bond network.