Polyborates in aqueous borate solution: A Raman and DFT theory investigation

The geometries, energies and vibrational frequencies of various polyborates in both gaseous and aqueous phase were calculated at the B3LYP/aug-cc-pVDZ level. The calculated total symmetrical stretching Raman shifts of B(OH)(3), B(OH)(4)(-), B2O(OH)(4), B2O(OH)(5)(-), B2O(OH)(6)(2-), B3O3(OH)(3), B3O3(OH)(4)(-), B3O3(OH)(5)(2-), B3O3(OH)(6)(3-), B4O5(OH)(4)(2-) and B5O6(OH)(4)(-) were assigned to 877.40, 735.33, 785.22, 792.90, 696.79, 587.72, 599.06, 740.16, 705.01, 551.67 and 521.04 cm(-1), respectively. The results can be used as the characteristic frequency for polyborates in aqueous phase at room temperature. At least six types of polyborates B(OH)(3), B(OH)(4)(-), B3O3(OH)(4)(-), B3O3(OH)(5)(2-), B4O5(OH)(4)(2-) and B5O6(OH)(4)(-), occur in aqueous solutions at ambient temperature. The chemical species distribution and the relevant interaction mechanisms among polyborates in the solutions were also suggested. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.