Influence of Substitution, Hybridization, and Solvent on the Properties of C−HO Single-Electron Hydrogen Bond in CH₃−H₂O Complex

Abstract

The effect of substitution, hybridization, and solvent on the properties of the C...HO single-electron hydrogen bond has been investigated with quantum chemical calculations. Methyl radical, ethyl radical, and vinyl radical are used as the proton acceptors and are paired with water, methanol, HOCl, and vinyl alcohol. Halogenation (Cl) of the proton donor strengthens this type of hydrogen bond. The methyl group in the proton donor and proton acceptor plays a different role in the formation of the C...HO single-electron hydrogen bond. The former is electron-withdrawing, and the latter is electron-donating, both making a constructive contribution to the enhancement of the interaction. The contribution of the methyl group in the proton acceptor is larger than that in the proton donor. The increase of acidity of the proton is helpful to form a single-electron hydrogen bond. As the proton acceptor varies from the methyl radical to the vinyl radical, the interaction strength also increases. The solvent has an enhancing influence on the strength of the C...HO single-electron hydrogen bond. These factors affect the C...HO single-electron hydrogen bond in a similar way that they do other types of hydrogen bonds.

Regulating function of methyl group on the strength of dihydrogen bond in HBeH-HCCH and HMgH-HCCH complexes

“…The results showed that the methyl group in the proton donor (methanol) is electron-withdrawing, whereas that in the proton acceptor (DMSO) is electron-donating, both making a positive contribution to the formation of OH···O hydrogen bond. Similar results are also found in the C···HO single-electron hydrogen bond in CH 3 -H 2 O complex [25].…”

“…These results show that the presence of the methyl group in the proton acceptor enhances the strength of the dihydrogen bond, whereas the presence of an electron-withdrawing group (F) weakens the strength of the dihydrogen bond. Such substitution effect is similar to that in other types of hydrogen bonds [22][23][24][25]34,35].…”

“…Although the elements directly participating in the formation of hydrogen bond play a main role in the formation of a hydrogen bond, the substituted methyl groups also have a non-negligible influence on the properties and structures of hydrogen-bonded complexes [19][20][21][22][23][24][25]. For example, the strength of hydrogen bond between pterin and nucleobases was enhanced as pterin was joined with two methyl groups [19].…”

The structure, properties, and nature of unconventional π halogen bond in the complexes of Al 4 2- and halohydrocarbons

“…In most cases, the interaction energy in the C(sp) complex is largest, followed by the C(sp 2 ) complex, and that in the C(sp 3 ) complex is smallest. This is similar to that in C-H hydrogen bonds [57][58][59][60][61] and Au-bonding [62]. One exception is that the interaction energy in Al 4 2-···Br-ethenec complex is less negative than that in the corresponding C(sp 3 ) complex.…”

Nonadditivity of methyl group in single‐electron hydrogen bond of methyl radical‐water complex

“…The CH 3 OH 2 O complex is most interested because water is a ubiquitous solvent in biological systems. In the previous article, the effect of substitution, hybridization, and solvent on the properties of C⅐⅐⅐HO single-electron hydrogen bond in the CH 3 OH 2 O complex has been investigated with method of quantum chemical calculations [23].…”