Mol­ecular and crystal structure, lattice energy and DFT calculations of two 2′-(nitro­benzo­yloxy)aceto­phenone isomers

The two isomers 2′-(4-nitro­benzo­yloxy)aceto­phenone (systematic name: 2-acetyl­phenyl 4-nitro­benzoate) (I) and 2′-(2-nitro­benzo­yloxy)aceto­phenone (systematic name: 2-acetyl­phenyl 2-nitro­benzoate) (II), both C15H11NO5, with para and ortho positions of the nitro substituent have been crystallized and studied. It is evident that the variation in the position of the nitro group causes a significant difference in the mol­ecular conformations: the dihedral angle between the aromatic fragments in the mol­ecule of I is 84.80 (4)°, while that in the mol­ecule of II is 6.12 (7)°. Diffraction analysis revealed the presence of a small amount of water in the crystal of I. DFT calculations of the mol­ecular energy demonstrate that the ortho substituent causes a higher energy for isomer II, while crystal lattice energy calculations show that the values are almost equal for two isomers.