Methyl groups as widespread Lewis bases in noncovalent interactions

Abstract It is well known that, under certain conditions, C( sp 3 ) atoms behave, via their ?-hole, as Lewis acids in tetrel bonding. Here, we show that methyl groups, when bound to less electronegative than carbon, can counterintuitively participate noncovalent interactions electron density donors. Thousands of experimental structures are found which groups behave bases establish alkaline, alkaline earth, triel, tetrel, pnictogen, chalcogen and halogen bonds. Theoretical calculations confirm the high directionality significant strength arise from a common pattern based on holes model. Moreover, despite absence lone pairs, able transfer charge ? bonding orbitals into empty electrophile reinforce attractive interaction.