Calculations of reduced partition function ratios of hydrated monoborate anion by the ab initio molecular orbital theory

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 monoborate anion (B(OH)(4)(-)) is evaluated in order to better understand boron isotope fractionation observed in aqueous systems. Aquoborate anions up to decaaquoborate anion, B(OH)(4)(-)(H2O)(10), were considered and their geometry optimization and RPFR calculations were carried out. It was induced that hydration decreased the ln(RPFR) value of B(OH)(4)(-) by ca. 1.2%.