Experimental

R factor = 0.054; wR factor = 0.155; data-to-parameter ratio = 15.1. In the title compound, C19H20F2N2O, the six-membered piperazine group adopts a slightly distorted chair conforma-tion. The dihedral angle between the mean planes of the two benzene rings is 73.4 (6). The mean plane of the ethanone group is twisted from the mean planes of the two benzene rings by 66.7 (8) and 86.2 (6). In the crystal, C—H O and C—H F interactions link the molecules, forming a three-dimensional structure. Related literature For the biological activity of piperazines, see: Bogatcheva et al. (2006); Brockunier et al. (2004). For a review of pharmaco-logical and toxicological information for piperazine deriva-tives, see: Elliott (2011). For related structures, see: Betz et al