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Hydrogen-hydrogen bonding: a stabilizing interaction in molecules and crystals.
Chérif F Matta1, Jesús Hernández-Trujillo, Ting-Hua Tang
1Chemistry Department, Lash Miller Chemical Laboratories, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|May 13, 2003
Summary
Hydrogen-hydrogen (H-H) interactions are stabilizing, not repulsive, contributing energy to molecules. These ubiquitous interactions are distinct from dihydrogen bonding and influence crystal sublimation energies.
Area of Science:
- Physical Chemistry
- Quantum Chemistry
- Computational Chemistry
Background:
- Traditional views often consider close-contact hydrogen atoms as purely repulsive.
- The presence of bond paths between hydrogen atoms suggests a more complex interaction.
- Understanding these interactions is crucial for molecular stability and crystal properties.
Purpose of the Study:
- To investigate the nature of interactions between bonded hydrogen atoms with similar charges.
- To determine if these H-H interactions are stabilizing or destabilizing.
- To differentiate H-H interactions from dihydrogen bonding.
Main Methods:
- Utilized the Quantum Theory of Atoms in Molecules (QTAIM) framework.
- Analyzed bond paths and electron density distributions.
- Calculated energy contributions and surface virial for H-H interactions.
Main Results:
- Identified stabilizing H-H interactions in various molecules (biphenyl, phenanthrene, etc.).
- Showed these interactions contribute up to 10 kcal mol(-1) stabilization energy.
- Demonstrated that attractive proton-electron density interactions dominate over repulsion.
Conclusions:
- H-H interactions are a ubiquitous stabilizing force in molecules.
- These interactions contribute significantly to the sublimation energies of hydrocarbon crystals and solid hydrogen.
- H-H bonding is fundamentally different from dihydrogen bonding.