Beryllium ion coordination in Ammonia, methanol and water solvents

Abstract

• Be is a key component of materials indispensable in today’s industries and its solvation behavior is a topic of interest. • The study highlight the coordination behavior of beryllium ion with water, ammonia and methanol solvents. • Fitting procedure to obtain Binding energy convergence. • Temperature effects on the isomeric distribution for each cluster size. • MP2 method as reliable method to describe the solvation process around cations. The solvation of B e 2 + [ M g N H 3 n = 1 - 10 ] 2 + cation in ammonia, methanol and water has been studied at Ab initio MP2 level using cluster models in which the solvent molecules have been distributed between the first and second solvation shells. In all cases, the first solvation sphere results to be saturated with four solvent molecules in a tetrahedral arrangement. The second shell contains instead up to 8,12 and 16 ligands in the case of methanol, water and ammonia, respectively. Solvent molecules in the second solvation shell serve to stabilizes the structures through the formation of a number of hydrogen bonds and improves the agreement with the available experimental data. From obtained distances values it can be deduced that beryllium ion establishes with the solvent molecules, inside the first coordination shell, bonds of covalent nature (less than1.8Å) which are longer than those with the magnesium ion. Using a fitting procedure, binding energy values of 29.2, 46.9 and 68.6 kcal/mol, for ammonia, water and methanol clusters, have been obtained, respectively. The clustering enthalpies and free energies have been also evaluated. Temperature effects on the isomeric distribution for each cluster and for all considered solvents, have been calculated in the range of 25–40 K and results show that only the tetracoordinated systems are populate.