Hydration Energies of Calcium Hydroxide Cation, CaOH+(H2O)x (x = 1–6), Studied Using Guided Ion Beam Tandem Mass Spectrometry
Research by Fan Yang and Peter B. Armentrout
Department of Chemistry
Hydrated metal and metal hydroxide ions are involved in critical reactions for delivering these metals to active biological sites. In recent work (Int. J. Mass Spectrom. 2024, 503, 117284.), guided ion beam tandem mass spectrometry was used to study the thermochemistry of CaOH+(H2O)x complexes, finding that the dominant reaction is the loss of a single water molecule as shown above for CaOH+(H2O)6. Analysis of the kinetic energy dependence for these dissociation processes provides experimental hydration energies of CaOH+ for 1–6 water ligands. These compare favorably to theoretical values obtained using CHPC resources (see below). These calculations also provide insight into the structures of these complexes. For instance, hydrogen bonding between the water and hydroxide ligands (dashed lines) stabilize these complexes.
