PNNL

Abstract

ABSTRACT: We report a combined negative ion photoelectron spectroscopy and theoretical investigation on a series of size-selected hydrated closo-dodecaborate 2- clusters B12X12 ·nH2O (X = H, F, I; n = 1 – 6). Distinct structural arrangements of 2- water clusters from monomer to hexamer can be achieved by using different B12X12 bases (X = H, F, I), illustrating evident solute specificity. Due to the superior strength of B-H···H-O dihydrogen bonds (solute – solvent) versus conventional O···H-O hydrogen bonds in water (solvent – solvent), the added water molecules are arranged in a unified binding mode by forming highly structured water networks manipulated by 2-. As a comparison, the hydrated B F 2- clusters display similar water B12H12 12 12 evolution patterns for monomer and dimer, but different binding modes for larger 2- clusters, while the hydrated B12I12 share similarities with the free water clusters. The present finding provides a consistent picture of the structural diversity of the hydrogen- bonding networks in the microhydrated dodecaborate clusters, and a molecular-level understanding of the microsolvation dynamics in aqueous borate chemistry.