The structure of the amide unit is almost planar. <...> The dihedral angles of the amide plane with the benzene and pyridine rings are 58.40(5)° and 61.51(5)° respectively, indicating that neither phenyl nor pyridyl group is conjugated with the amide unit. <...> The conformation of the carbonyl group in N,N-diarylamides has received interest due to their reactivities [ 1 ]. <...> The conformation where the oxygen atom of the carbonyl group has a close contact with an electron-deficient aryl group is considered to be favorable because of the effective conjugation and an intramolecular hydrogen bond with the aryl group. <...> We report the structure and DFT study of N-phenyl-N-(pyridin-4-yl)acetamide (1) where a phenyl group of diphenylacetamide is replaced by the pyridyl group. <...> The positions of the C-bound H atoms were obtained by the calculation and were refined as riding on their parent C atoms. <...> Uiso(H) values of the H atoms were set at 1.2Ueq (parent atom for C). <...> The dihedral angles of the amide plane with the benzene and pyridine rings are 58.40(5)° and 61.51(5)° respectively, indi© Umezono S., Okuno T., 2015 ЖУРНАЛ СТРУКТУРНОЙ ХИМИИ Май – июнь КРАТКИЕ СООБЩЕНИЯ С. 502 – 504 ЖУРНАЛ СТРУКТУРНОЙ ХИМИИ. 2015. <...> Intermolecular contacts: C2—H2 cating that neither phenyl nor pyridyl group is well conjugated with the amide unit. <...> The oxygen atom of the carbonyl group has the same side with the pyridyl ring, but intramolecular hydrogen bonds cannot be recognized. <...> Conformer I was estimated to be more stable than conformer II by 7.4 kJ⋅mol–1, and the energy difference indicated little population of conformer II at room temperature. <...> In conformer I, the pyridyl group has a smaller angle (ca 25.4°) with the amide plane, although the phenyl group has a larger angle (ca 75.6°) with the plane. <...> The smaller dihedral angle of the pyridyl ring is thought to originate in the intramolecular C—H ⋯ O hydrogen bond and also in the effective conjugation between the nitrogen lone pair and the ring. <...> In diarylacetamide derivatives, the dihedral angles of the aryl groups with the amide plane indicate a tendency that the relatively electron-deficient ring has a smaller angle [ 1, 8, 9 ]. <...> However, in 1 <...>