The crystal structure of N-((4-chloro-5-(3-nitrophenyl)-2H-1,2,3-triazol-2-yl)methyl)acetamide, C₁₁H₁₀ClN₅O₃

1 Source of materials

In a 50 mL Schlenk tube, 0.11 g (0.454 mmol) of [4-(3-nitro-phenyl)-[1,2,3]triazol-2-yl]-methanol, 90.7 mg (0.682 mmol) of 1-chloropyrroline-2,5-dione, and 14.89 mg (0.091 mmol) of 2,2-azobisisobutyronitrile were added, followed by 6.0 mL of acetonitrile. The reaction was carried out at 110° for 20 h. The resulted mixture was cooled to room temperature and the solvent was removed under reduced pressure to obtain crude product NTA. ⁷ The crude product was eluted with a mixed solvent of petroleum ether and ethyl acetate (V/V = 4:1) and subjected to silica gel column chromatography to obtain the titled compound as a white solid (86.1 mg, yield: 55 %). Crystals of the titled compound were grown through slow evaporation of a methanol/dichloromethane mixed solution (V/V = 1:1) at 25 °C for five days.

2 Experimental details

H atoms bonded to C atoms were located in difference maps and subsequently treated as riding, with C–H distances of 0.95 Å (aromatic), 0.99 Å (methylene) and 0.98 Å (methyl), respectively. U_iso(H) = 1.2U_eq (aromatic and methylene C) and 1.5U_eq (methyl C). H atoms bonded to N atoms can be also initially found in difference maps and then restrained to be at their ideal positions with U_iso(H) = 1.2U_eq = (N5).

3 Comments

2,4-disubstituted-1,2,3-triazole derivatives have a wide range of biological activities. ^{8 , 9} Introducing some certain amide or hydrazide substructures on the 1,2,3-triazole ring is one of the approaches to developing novel 1,2,3-triazole antibacterial agents. As a continued study of one of our previous works, ^{10 , 11} we have synthesized a new triazole functionalized compound, N-((4-chloro-5-(3-nitrophenyl)-2H-1,2,3-triazol-2-yl)methyl)acetamide (NTA).

In the asymmetric unit of the title structure, there is one discrete NTA molecule. The nitrobenzene ring and the triazole ring are almost coplanar. Among all the atoms constituting the plane, the O1 atom is the farthest from this plane with a distance of merely 0.26 Å. The plane formed by the four atoms of the acetamide (N5/O3/C10/C11) is almost perpendicular to the plane discussed above with a dihedral angle 85.78(1)° between them. This should be attributed to the formation of intermolecular hydrogen bonds in which the acetamide N5 atom acts as a donor being hydrogen-bonded to the O3 at (x−1, y, z) with a N5⋯O3 distance of 2.821(2) Å. Apart from this distinction, the bond lengths and bond angles are comparable to some analogous. ¹²

In the crystal packing, except for the above mentioned intermolecular N5⋯O3 hydrogen bonds, there is another intermolecular π⋯π stacking interaction, further stablizing the crystal structure. In more details, the interaction exists between the benzene ring and the adjacent triazole ring with the centroid-to-centroid distance being 3.742(2) Å, further forming a one-dimensional array along the [100] direction. ^{7 , 13}