Comparative study of resonance-inhibited hydrogen bonded (RIHB) systems with different atoms involved: the leading role of σ-planarity

O, S, Se, and P atoms are considered as different proton donor/acceptor moieties in the resonance-inhibited hydrogen bonded (RIHB) interactions to conduct a comparative investigation. In order to study the effects of resonance and σ-skeleton planarity, the corresponding saturated and planar molecules are also computed. Moreover, to provide a broader perspective, all the given systems are compared to their resonance-assisted hydrogen bonded (RAHB) analogues. The natural bond orbital (NBO), the quantum theory of atoms in molecule (QTAIM), and the gauge-independent atomic orbital (GIAO) analyses, are performed to estimate the strength and nature of the intramolecular hydrogen bonds (IMHBs). The strength of IMHBs is also estimated using energy differences between closed and open conformers. According to the results, all the given RIHB systems suggest that resonance can obviously decrease the strength of the IMHBs. However, in the RIHB systems and also in some RAHB ones, the role of π-conjugation in the IMHB formation is less important than that of σ-planarity. In other words, the constraints imposed by σ-skeleton cause both the H-bond acceptor and donor groups to be situated close to each other; these effects outweigh the undesirable results of resonance, which totally lead to the formation of the RIHB.