5-Pyridine 4-yl-3H-(1,3,4) Oxadiazole-2 Thione Hydrochloride Monohydrate, (I), and 4 [5-Ethylsulfanyl)-(1,3,4) Thiadiazole-2-yl]-Pyridinium Perchlorate, (II)

The title compounds C7H8ClN3O2S, (I), and C9H10ClN3O4S2, (II), both crystallize in monoclinic space group P2(1) /c with unit cell parameters (I) a = 7.9402(7), b = 10.6312(9), c = 11.7626(10), , beta = 99.271(5)A degrees, Z = 4 and (II) a = 5.1439(2), b = 9.0636(4), c = 27.1814 (7), , beta = 95.116(2)A degrees, Z = 4. In (I) the molecule consists of a 5-pyridine-4-yl group bonded to the carbon atom at the 5 position of (1, 3, 4) oxadiazole-2 thione hydrochloride monohydrate. The angle between the mean planes of the oxadiazole and pyridine rings is 9.6(6)A degrees. Crystal packing in (I) is stabilized by strong N-H center dot center dot center dot O hydrogen bonds in concert with a solvent water molecule and weak O-H center dot center dot center dot Cl, O-H center dot center dot center dot S, N-H center dot center dot center dot Cl intermolecular interactions. The crystal structure of compound (II) consists of 4 [5-ethylsulfanyl)-(1, 3, 4) thiadiazole-2-yl]-pyridinium perchlorate, (C9H10N3S2)(+)(ClO4)(-), cation-anion pairs, containing strong intermolecular N-H center dot center dot center dot O hydrogen bonds and weak C-H center dot center dot center dot O and N-H center dot center dot center dot O intermolecular interactions operating between the ionic species that form a cooperative hydrogen-bonded, infinite chain O-H center dot center dot center dot O-H center dot center dot center dot O-H network which generates a sheet motif structure in the unit cell. It is also supported by weak intermolecular Cg center dot center dot center dot Cg pi-pi and Cl-O center dot center dot center dot Cg pi-ring interactions which gives additional support to molecular packing stability in the unit cell. Geometry optimized MOPAC AM1 computational calculations on each compound provides support to the structural features in their respective crystal structures. The crystal structures of 5-Pyridine 4-yl-3H-(1,3,4) oxadiazole-2 thione hydrochloride monohydrate, C7H8ClN3O2S, (I), and 4 [5-Ethylsulfanyl)-(1,3,4) thiadiazole-2-yl]-pyridinium perchlorate, C9H10ClN3O4S2, (II) are investigated. Both molecules crystallize in the monoclinic space group P2(1) /c. Crystal packing in (I) is stabilized by strong N-H center dot center dot center dot O hydrogen bonds in concert with a solvent water molecule and weak O-H center dot center dot center dot Cl, O-H center dot center dot center dot S, N-H center dot center dot center dot Cl intermolecular interactions. The crystal structure of compound (II) consists of cation-anion pairs, (C9H10N3S2)(+)(ClO4)(-), containing strong intermolecular N-H center dot center dot center dot O hydrogen bonds and weak C-H center dot center dot center dot O and N-H center dot center dot center dot O intermolecular interactions operating between the ionic species which form a cooperative hydrogen-bonded, infinite chain O-H center dot center dot center dot O-H center dot center dot center dot O-H network which generates a sheet motif structure in the unit cell. The geometric and packing parameters of both structures are described and compared to a MOPAC AM1 computational calculations on each compound provides support to the structural features in their respective crystal structures.