Crystal structures of an imidazo[1,5-a]pyridinium-based ligand and its (C(13)H(12)N(3))(2)[CdI(4)] hybrid salt

The monocation product of the oxidative condensation–cyclization between two mol­ecules of pyridine-2-carbaldehyde and one mol­ecule of CH(3)NH(2)·HCl in methanol, 2-methyl-3-(pyridin-2-yl)imidazo[1,5-a]pyridinium, was isolated in the presence of metal ions as bis­[2-methyl-3-(pyridin-2-yl)imidazo[1,5-a]pyridin-2-ium] tetra­iodo­cadmate, (C(13)H(12)N(3))(2)[CdI(4)], (I), and the mixed chloride/nitrate salt, bis­[2-methyl-3-(pyridin-2-yl)imidazo[1,5-a]pyridin-2-ium] 1.5-chlor­ide 0.5-nitrate trihydrate, 2C(13)H(12)N(3) (+)·1.5Cl(−)·0.5NO(3) (−)·3H(2)O, (II). Hybrid salt (I) crystallizes in the space group P2(1)/n with two [L](2)[CdI(4)] mol­ecules in the asymmetric unit related by pseudosymmetry. In the crystal of (I), layers of organic cations and of tetra­halometallate anions are stacked parallel to the ab plane. Anti­parallel L (+) cations disposed in a herring-bone pattern form π-bonded chains through aromatic stacking. In the inorganic layer, adjacent tetra­hedral CdI(4) units have no connectivity but demonstrate close packing of iodide anions. In the crystal lattice of (II), the cations are arranged in stacks propagating along the a axis; the one-dimensional hydrogen-bonded polymer built of chloride ions and water mol­ecules runs parallel to a column of stacked cations.