Benchmark binding energies of ammonium and alkyl-ammonium ions interacting with water. Are ammonium–water hydrogen bonds strong?

Valérie Vallet (1) , Michel Masella (2)

1 PCMT - Physico-Chimie Moléculaire Théorique
2 IBITECS - Institut de Biologie et de Technologies de Saclay

Alkyl-ammonium ion/water interactions are investigated using high level quantum computations, yielding thermodynamics data in good agreement with gas-phase experiments. Alkylation and hydration lead to weaken the NH O hydrogen bonds. Upon complete hydration by four water molecules, their main features are close to those of the OH O bond in the isolated water dimer. Energy decomposition analyses indicate that hydration of alkyl-ammonium ions are mainly due to electrostatic/polarization effects, as for hard monoatomic cations, but with a larger effect of dispersion.

Domaines: Chimie-Physique [physics.chem-ph]

Valérie Vallet, Michel Masella. Benchmark binding energies of ammonium and alkyl-ammonium ions interacting with water. Are ammonium–water hydrogen bonds strong?. Chemical Physics Letters, 2015, 618, pp.168-173. ⟨10.1016/j.cplett.2014.11.005⟩. ⟨hal-01185327⟩