Evidence of the Elusive Gold-Induced Non-classical Hydrogen Bonding in Aqueous Environments

The ability of a gold ion to act as a proton acceptor in hydrogen bonding continues to remain an open question. Heavy-atom effects and secondary competitive interactions in gold complexes make it challenging to precisely establish the identity of gold-ion-induced hydrogen bonding via experimental techniques. In such situations, computational chemistry may play an important role. Herein we have performed Born-Oppenheimer molecular dynamics simulations to study the behavior of [Au(CH₃)₂)]^- in bulk and interfacial aqueous environments. The simulation results suggest that the [Au(CH₃)₂)]^- complex forms one and two gold-ion-induced hydrogen bonds with the water molecules in interfacial and bulk environments, respectively. The calculated probabilities of key hydrogen-bonded configurations of [Au(CH₃)₂)]^-, combined distribution functions, and diffusion coefficients further support this unusual hydrogen-bonding interaction. In summary, the present results suggest that gold-ion-induced hydrogen bonding in an actual solvent environment may be feasible. These results will improve our understanding about the role of weak interactions in transition metal complexes and, thus, will have implications in catalysis and supramolecular assemblies.