2-(1H-Pyrazol-3-yl)pyridinium chloride monohydrate

5-Amino-3-(4H-1,2,4-triazol-4-yl)-1H-1,2,4-triazole

The asymmetric unit of the title compound, C₄H₅N₇, comprises two independent but virtually superimposable mol­ecules. Each mol­ecule is planar with the dihedral angles between the five-membered rings being 2.8 (3) and 2.1 (3)°. The crystal structure is formed by an extensive network of relatively strong N—H⋯N hydrogen-bond inter­actions. Individual mol­ecules are arranged into supra­molecular zigzag chains running parallel to [001] by way of the strongest N—H⋯N inter­actions. Adjacent chains are inter­connected by rather long (D⋯A distances range from ca 3.00 to 3.03 Å) but highly directional (inter­action angles above ca 173°) hydrogen bonds forming a supra­molecular layer in the bc plane.

4,4'-Di-tert-butyl-2,2'-dipyridinium dichloride

In the title compound, C₁₈H₂₆N₂²⁺·2Cl⁻, the complete dication is generated by crystallographic inversion symmetry; both N atoms are protonated and engaged in strong and highly directional N—H⋯Cl hydrogen bonds. Additional weak C—H⋯Cl contacts promote the formation of a tape along ca. [110]. The crystal structure can be described by the parallel packing of these tapes. The crystal studied was a non-merohedral twin with twin law [−1 0 0, 0 −1 0, −0.887 0.179 1] and the final BASF parameter refining to 0.026 (2) .

5-Amino-1H-1,2,4-triazol-4-ium-3-carboxyl-ate hemihydrate

The asymmetric unit of the title compound, C(3)H(4)N(4)O(2)·0.5H(2)O, comprises two whole mol-ecules of 5-amino-1H-1,2,4-triazole-3-carb-oxy-lic acid in its zwitterionic form (proton transfer occurs from the carb-oxy-lic acid group to the N hetero-atom at position 1), plus one water mol-ecule of crystallization. The organic moieties are disposed into supra-molecular layers linked by N-H⋯O and N-H⋯N hydrogen bonds parallel to the bc plane. Additional O-H⋯O and N-H⋯O hydrogen bonds involving the water mol-ecules and the organic mol-ecules lead to the formation of double-deck supra-molecular arrangements which are inter-connected along the a axis via π-π stacking [centroid-centroid distance = 3.507 (3) Å].

4-Phenyl-1-(prop-2-yn-1-yl)-1H-1,5-benzodiazepin-2(3H)-one

4-Phenyl-1H-1,5-benzodiazepin-2(3H)-one reacts in the pres­ence of a concentrated aqueous solution of sodium hydroxide and a quaternary ammonium salt (as catalyst) in benzene (phase transfer catalysis) with propargyl bromide, affording the title benzodiazepine derivative, C₁₈H₁₄N₂O. In the mol­ecule, the mean plane of the propargyl substituent is almost perpendicular with that of the amide group [dihedral angle = 87.81 (8)°]. In the crystal, the molecules are linked by C—H⋯O and C—H⋯N inter­actions.