The C–H⋯π bonds: strength, identification, and hydrogen-bonded nature: a theoretical study

Using the MP2 method and, in some cases, a basis set-up to aug-cc-pVTZ quality, the properties of C–H⋯π bonds have been investigated in model dimers. Their strength goes from 0.55 up to 2.5 kcal/mol, depending on the C–H carbon hybridization and the π system. The presence of these bonds is identified by the presence of a bond critical point linking the H atom and atoms of the π system. The critical point characteristics and the vibrational shift of the C–H⋯π bonded dimers are similar to those present in C–H⋯O and O–H⋯π hydrogen-bonded dimers, thus indicating a hydrogen-bonded nature.