Hydrogen–Hydrogen Bonds in Highly Branched Alkanes and in Alkane Complexes: A DFT, ab initio, QTAIM, and ELF Study

Abstract

The hydrogen-hydrogen (H-H) bond or hydrogen-hydrogen bonding is formed by the interaction between a pair of identical or similar hydrogen atoms that are close to electrical neutrality and it yields a stabilizing contribution to the overall molecular energy. This work provides new, important information regarding hydrogen-hydrogen bonds. We report that stability of alkane complexes and boiling point of alkanes are directly related to H-H bond, which means that intermolecular interactions between alkane chains are directional H-H bond, not nondirectional induced dipole-induced dipole. Moreover, we show the existence of intramolecular H-H bonds in highly branched alkanes playing a secondary role in their increased stabilities in comparison with linear or less branched isomers. These results were accomplished by different approaches: density functional theory (DFT), ab initio, quantum theory of atoms in molecules (QTAIM), and electron localization function (ELF).

Cooperativity between the halogen bonding and halogen–hydride bonding in NCX⋯NCX⋯HMgY complexes (X=F, Cl, Br; Y=H, F, Cl, Br, CH3, Li)

“…The ELF values are within a range of 0-1, where the tendency to zero means that parallel spins are highly probable, while the tendency to one indicates a high probability of opposite spin pairs [66]. The ELF method was applied to analyze different types of interactions, for instance, recently the ELF is employed in order to analyze the hydrogenhydrogen bond [66].…”

Conformation preference and related intramolecular noncovalent interaction of selected short chain chlorinated paraffins

“…Such H···H contact is not a typical donor-acceptor interaction with charge-transfer potential since the two hydrogen atoms bearing identical charge are somehow chemically equivalent. The most recently reported study on the C 8 H 18 isomers shows that the existence of intramolecular H···H bonds in highly branched alkanes plays a secondary role in their increased stabilities in comparison with linear or less branched isomers [20]. Hence the stability of the tGt conformer, higher than that of g′Tt, is expected due to the relatively strong attraction capacity of H 18 ···H 24 contact with its obvious low ellipticity .…”

“…Moreover, in addition to weak hydrogen bonds with controversial features, other types of intramolecular NCIs may also appear in halogenated alkanes to maintain the specific conformations. Various calculation results show that intramolecular H-H bonds can be formed in highly branched alkanes and yield a stabilizing contribution to their increased stabilities in comparison with linear or less branched isomers [20]. Most recently, an attractive intramolecular halogen-halogen bonding interaction has been reported to assist in stabilizing the molecules of perhalogenated ethanes.…”

“…The theory of "atoms in molecules" (AIM) has been used to characterize noncovalent interactions like such hydrogen bonding interactions and allows a hydrogen bond distinguished from a van der Waals interaction [22,23]. Monteiro and Firme's work [20] showed that the hydrogen-hydrogen bonds in alkane complexes play a role in their stabilities and their boiling points by using density functional theory (DFT), ab initio, quantum theory of atoms in molecules (QTAIM), and electron localization function (ELF). Johansson and Swart's study [21] showed that non-covalent halogen-halogen interaction in the perhalogenated ethanes is real and attractive with appreciable strength, when one of the halogens involved is chlorine.…”

On atom–atom `short contact' bonding interactions in crystals

“…Often, discrepancies between classical models and what the observable topology and topography of (r) is telling us turn out to be cases of great interest. An example is the concept of HÁ Á ÁH bonding (Cukrowski & Matta, 2010;Herná ndez-Trujillo & Matta, 2007;Matta et al, 2003), which after a wave of initial criticism, as it violates classical models, has growingly proved to be useful, predictive, and consistent with observation (Paul et al, 2011;Echeverría et al, 2011;Monteiro & Firme, 2014;Sabirov, 2014). In the case of challenging experimental charge density determinations, such as those describing halogen and chalcogen heavy atoms involved in very weak interactions, the experimental properties of the topology of (r) in the intermolecular regions are systematically supported by theoretical calculations and vice versa.…”