Synthesis, crystal structure, DFT calculations and Hirshfeld surface analysis of 3-butyl-2,6-bis(4-fluorophenyl)piperidin-4-one

Abstract

The title compound, C21H23F2NO, consists of two fluorophenyl groups and one butyl group equatorially oriented on a piperidine ring, which adopts a chair conformation. The dihedral angle between the mean planes of the phenyl rings is 72.1 14;(1)°. In the crystal, N-H..O and weak C-H..F interactions, which form R 2 2[14] motifs, link the molecules into infinite C(6) chains propagating along [001]. A weak C-H..p interaction is also observed. A Hirshfeld surface analysis of the crystal structure indicates that the most significant contributions to the crystal packing are from H..H (53.3%), H..C/C..H (19.1%), H..F/F..H (15.7%) and H..O/O..H (7.7%) contacts. Density functional theory geometry-optimized calculations were compared to the experimentally determined structure in the solid state and used to determine the HOMO-LUMO energy gap and compare it to the UV-vis experimental spectrum.