Calculations of Reduced Partition Function Ratios of Hydrated Boric Acid Molecule by the ab initio Molecular Orbital Theory

Abstract

Based on the ab initio molecular orbital theory at the HF/6-31G(d) level, the effect of hydration on the reduced partition function ratio (RPFR) of the boric acid molecule (B(OH)3) was evaluated in order to better understand boron isotope fractionation observed in aqueous systems. The B(OH)3(H2O) n species with n up to 12 were considered and their geometry optimization and RPFR calculations were carried out. It was induced that hydration decreased the RPFR of B(OH)3 and the degree of decrease in ln(RPFR) was ca. 1.5%, which was nearly equivalent to that of B(OH)4 -.