IRM@Be2+ – quantum chemistry between Bavaria and Šumadija

Abstract

Quantum chemical (density functional theory) mechanistic investigations on ligand exchange reactions at a tetrahedrally-coordinated dicationic Beryllium center offer a harmless and alternative way to learn about the traversed reaction pathways compared to experimental studies. Calculations for solvent exchange at [Be(H2O)4]2+, [Be(NH3)]2+, and [Be(HCN)4]2+ showed interchange (I) type mechanisms. To learn about the potential influences of spectator ligands we calculated the water exchange at [Be(L)(H2O)3]n+ (L: neutral ligands, mono-anionic ligands or cationic ligands) and got again consequently I-type paths. The activation energies depend strongly on the starting complexes, e.g., if hydrogen bonds have to be broken. The influence of spectator ligands is limited to the charge of the ligand and therefore the overall charge of the beryllium complex. The small size of the beryllium solvent complexes allows to test tools like AIM to dissect between pure interchange mechanisms, associative mechanisms and dissociative interchange mechanisms based on electron density along the reaction pathway.