Probing "hydridic hydrogen bonds" using energy decomposition analysis based on absolutely localized molecular...

Area of Science:

• Computational chemistry
• Quantum chemistry
• Supramolecular chemistry

Background:

• The concept of "hydridic hydrogen bonds" (HBs) describes X-H⋯Y interactions where X is more electropositive than H.
• These interactions are proposed to differ from conventional protonic HBs.

Purpose of the Study:

• To investigate the physical origin of "hydridic HBs" using trimethylsilane as a model.
• To analyze the factors contributing to vibrational frequency shifts in these interactions.

Main Methods:

• Energy Decomposition Analysis (EDA) based on Absolutely Localized Molecular Orbitals (ALMO-EDA).
• Adiabatic ALMO-EDA was employed to study frequency shifts.

Main Results:

• "Hydridic HB" complexes show a greater contribution from dispersion interactions compared to protonic HBs.
• Polarization and charge-transfer effects in "hydridic HBs" originate from the electron-rich Si-H bond.
• Permanent electrostatics and charge transfer are key drivers for Si-H stretching frequency redshifts.

Conclusions:

• The physical origins of "hydridic HBs" are fundamentally different from conventional protonic HBs.
• Alternative terminology, such as "hydride bonds" or bonds named after the H-acceptor (e.g., tetrel bonds), should be considered.