Electrostatic Potential at Atomic Sites as a Reactivity Descriptor for Hydrogen Bonding. Complexes of Monosubstituted Acetylenes and Ammonia

Abstract

The applicability of molecular electrostatic potential values at atomic sites as a reactivity descriptor for the process of hydrogen bonding is assessed for a series of complexes involving acetylene and diacetylene derivatives as proton donors and ammonia as a model proton acceptor. The acetylenic compounds studied were of the type R−C⋮C−H, where R represents H, F, Cl, CH3, CH2F, CHF2, CF3, CH2Cl, CHCl2, CCl3, CN, H−C⋮C, F−C⋮C, Cl−C⋮C. Density functional theory computations at the B3LYP/6-31G(d,p) level were employed. An excellent linear relation between the molecular electrostatic potential at the acetylenic hydrogen atom in the isolated acetylenes with the energy of hydrogen-bond formation is found. It is concluded that the value of the electrostatic potential at the acidic hydrogen atomic site can be used as a reactivity descriptor for the hydrogen bonding ability of the molecules studied.