title: Density functional theory study on the bridge structure in dimeric aluminum (III) water complexes.
abstract: Density-functional theory methods were used to investigate the structure of dimeric aluminum (III) water complexes as a function of bridging group. The possibilities of oxygen, water, and hydroxyl bridge ligands and a variety of structural arrangements, such as cis/trans, with respect to the relative position of hydroxyl ligands, were considered. Within the limit of our computational level, we found that electrostatic repulsion between hydroxyls is important in deciding the polyaluminum structure. Although the structures of aluminum-hexaaquo predominate, species with small number of charges or a large number of hydroxyl ligands have a tendency toward a five-coordinate trigonal bipyramidal configuration. Because water is electronically neutral, it cannot provide enough negative charges as a bridge ligand to stabilize two Al(III) molecules. The energy differences among many configurational isomers of hydroxyl Al are so small that they may coexist and convert into each other easily at room temperature.
authors.affiliation: State Key Laboratory of Coordination Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, People's Republic of China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Miao
authors.forename: Qing
authors.initials: Q
authors.lastname: Cao
authors.forename: Shuping
authors.initials: S
authors.lastname: Bi