Electron density topological analysis of the C–H⋯O anti-hydrogen bond in the fluoroform–oxirane complex

The C–H⋯O interaction in the fluoroform–oxirane complex has recently been shown to exhibit features of anti-hydrogen bonding, which is characterized by a shortening of the C–H bond and a blue-shift of the C–H stretching frequency. We present here the results of a topological analysis of the electron density following the theory of atoms in molecules in order to gain insight into the nature of the anti-hydrogen bond. The study is focused on the two energetically most stable complexes, which correspond to a planar complex with a colinear C–H⋯O bond, and a non-planar structure with a bent C–H⋯O bond. The origin of the anti-H bond is discussed in terms of the electron density changes induced upon complexation.