Mol-ecular and crystal structure, lattice energy and DFT calculations of two 2'-(nitro-benzo-yloxy)aceto-phenone...

The two isomers 2'-(4-nitro-benzo-yloxy)aceto-phenone (systematic name: 2-acetyl-phenyl 4-nitro-benzoate) (I) and 2'-(2-nitro-benzo-yloxy)aceto-phenone (systematic name: 2-acetyl-phenyl 2-nitro-benzoate) (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 mol-ecular conformations: the dihedral angle between the aromatic fragments in the mol-ecule of I is 84.80 (4)°, while that in the mol-ecule 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 mol-ecular 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.