Comparison of the CH and OH Groups as Proton Donors within Hydrogen Bonds

The ability of the CH group to act as proton donor is now widely accepted, even if the H bonds (HBs), which it forms are typically much weaker than those of the hydroxyl group, particularly for a sp3‐hybridized C. An NH3 nucleophile is allowed to approach both the terminal methyl group and the hydro...

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Main Authors: Savannah Rawlings, Steve Scheiner
Format: Article
Language:English
Published: Wiley-VCH 2025-07-01
Series:ChemistryEurope
Subjects:
Online Access:https://doi.org/10.1002/ceur.202500088
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author Savannah Rawlings
Steve Scheiner
author_facet Savannah Rawlings
Steve Scheiner
author_sort Savannah Rawlings
collection DOAJ
description The ability of the CH group to act as proton donor is now widely accepted, even if the H bonds (HBs), which it forms are typically much weaker than those of the hydroxyl group, particularly for a sp3‐hybridized C. An NH3 nucleophile is allowed to approach both the terminal methyl group and the hydroxyl of n‐butanol, so as to form either a CH··N or OH··N HB. Density functional theory calculations show that the latter is much stronger than the former. However, the strength of the CH··N HB can be amplified and approach much closer to that of OH··N by appropriate placement of suitable electron‐withdrawing and donating substituents on the butanol. The interaction energy of the CH··N HB reaches above 6–8 kcal mol−1 in several cases, considerably larger than the prototype HB within the water dimer.
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spelling doaj-art-6778ccc8dfbf45d59067e6da6e94ec212025-08-20T03:30:19ZengWiley-VCHChemistryEurope2751-47652025-07-0134n/an/a10.1002/ceur.202500088Comparison of the CH and OH Groups as Proton Donors within Hydrogen BondsSavannah Rawlings0Steve Scheiner1Department of Chemistry and Biochemistry Utah State University Logan UT 84322‐0300 USADepartment of Chemistry and Biochemistry Utah State University Logan UT 84322‐0300 USAThe ability of the CH group to act as proton donor is now widely accepted, even if the H bonds (HBs), which it forms are typically much weaker than those of the hydroxyl group, particularly for a sp3‐hybridized C. An NH3 nucleophile is allowed to approach both the terminal methyl group and the hydroxyl of n‐butanol, so as to form either a CH··N or OH··N HB. Density functional theory calculations show that the latter is much stronger than the former. However, the strength of the CH··N HB can be amplified and approach much closer to that of OH··N by appropriate placement of suitable electron‐withdrawing and donating substituents on the butanol. The interaction energy of the CH··N HB reaches above 6–8 kcal mol−1 in several cases, considerably larger than the prototype HB within the water dimer.https://doi.org/10.1002/ceur.202500088atoms in moleculesmolecular electrostatic potentialsnuclear magnetic resonance shieldingsredshifts
spellingShingle Savannah Rawlings
Steve Scheiner
Comparison of the CH and OH Groups as Proton Donors within Hydrogen Bonds
ChemistryEurope
atoms in molecules
molecular electrostatic potentials
nuclear magnetic resonance shieldings
redshifts
title Comparison of the CH and OH Groups as Proton Donors within Hydrogen Bonds
title_full Comparison of the CH and OH Groups as Proton Donors within Hydrogen Bonds
title_fullStr Comparison of the CH and OH Groups as Proton Donors within Hydrogen Bonds
title_full_unstemmed Comparison of the CH and OH Groups as Proton Donors within Hydrogen Bonds
title_short Comparison of the CH and OH Groups as Proton Donors within Hydrogen Bonds
title_sort comparison of the ch and oh groups as proton donors within hydrogen bonds
topic atoms in molecules
molecular electrostatic potentials
nuclear magnetic resonance shieldings
redshifts
url https://doi.org/10.1002/ceur.202500088
work_keys_str_mv AT savannahrawlings comparisonofthechandohgroupsasprotondonorswithinhydrogenbonds
AT stevescheiner comparisonofthechandohgroupsasprotondonorswithinhydrogenbonds