Crystal Structures of 1-Aryl-1H- and 2-Aryl-2H-1,2,3-triazolyl Hydrazones. Conformational Consequences of Different Classical Hydrogen Bonds

The crystal structures of (Z)-1-phenyl-4-[((2-phenylhydrazono) methyl)]-1H-1,2,3-triazole, (Z)-4-[(2-(2,4-dimethylphenyl)hydrazono)methyl]-2-phenyl-2H-1,2,3-triazole, (E)-4-[(2-(2,4-dinitrophenyl) hydrazono) methyl]-2-phenyl-2H-1,2,3-triazole, and (E)-N'-((2-phenyl-2H-1,2,3-triazol-4-yl) methylene) isonicotinohydrazide dihydrate are reported. The formations of (Z)-configurations about the C=N bonds in the first two compounds arise from the stabilizing presence of intramolecular N-H center dot center dot center dot N hydrogen bonds, while in the third compound, the presence of intramolecular N-H center dot center dot center dot O hydrogen bonds promotes an (E) geometry. The arrangement about the CONHC=N fragment in the hydrated acylhydrazone is E-C(O)NH/E-C=N. Also present in (E)-N'-((2-phenyl-2H-1,2,3-triazol-4-yl) methylene) isonicotinohydrazide is an interesting R-4(4)(8) ring formed from hydrogen bonds generated from four water molecules. Significant pi center dot center dot center dot pi stacking interactions are exhibited in three compounds, but not in the least planar first compound, in which the dominant intermolecular interactions are C-H center dot center dot center dot pi interactions. Other intermolecular interactions in one of the compounds are C-H center dot center dot center dot pi interactions, in another compound are C-H center dot center dot center dot O hydrogen bonds and N-O center dot center dot center dot pi interactions, and in the last compound are O-H center dot center dot center dot X (X = O and N), N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds.