title: Single ion and dimerization studies of the Al(III) ion in aqueous solution.
abstract: Aqueous trivalent aluminum (Al) ions and their oligomers play important roles in diverse areas, such as environmental sciences and medicine. The geometries of octahedral Al(H(2)O)(6)(3+) and tetrahedral Al(OH)(4)(-) species have been studied extensively. However, structures of intermediate hydrolysis products of the Al(III) ion, such as the penta-coordinated Al(OH)(2+) species, which exists at pH values ranging from 3.0 to 4.3, and their mode of formation have been poorly understood. Here, we present that a trigonal bipyramidal Al(OH)(H(2)O)(4)(2+) structure is formed in aqueous solution and how this monomeric species dimerizes to a dinuclear [(H(2)O)(4)Al(OH)(2)Al(H(2)O)(4)](4+) complex in aqueous solution. The Gibbs free energy change calculations indicate that the formation of the dinuclear complex is preferred over the existence of two single trigonal bipyramidal Al(OH)(H(2)O)(4)(2+) species in aqueous solution. This study captures the solution dynamics and proton transfer in the oligomerization reactions of penta-coordinated Al(OH)(2+) species in aqueous solution.
authors.affiliation: The University of Texas at San Antonio, Department of Chemistry, One UTSA Dr., San Antonio, Texas 78249, USA. orkid.coskuner@utsa.edu
authors.forename: Orkid
authors.initials: O
authors.lastname: Coskuner
mesh_terms: D000536:Aluminum Hydroxide / Q000737:chemistry*; D003198:Computer Simulation; D019281:Dimerization; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry*; D008958:Models, Molecular; D012996:Solutions; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D007477:Ions; D012996:Solutions; D014867:Water; D000536:Aluminum Hydroxide