Structure, bonding and redox properties of scandium oxide clusters, a model study

Abstract

A systematic survey of scandium oxide molecules and clusters was performed by means of density functional theory (DFT). Various types of scandium to oxygen bonding were characterized. Main features of the resulting menagerie of stable gas phase species are: (1) a basic Sc 2O 2 molecule with rhombic structure, (2) a highly symmetric Sc 2O 3 molecule with structure and D 3h symmetry, (3) an Sc 2O 4 dimer, which is an OSc–O–O–ScO analogue to hydrogen peroxide, and (4) the most stable cluster of Sc 2O 4 stoichiometry. The latter can be understood as two Sc atoms bridged by two oxygen atoms and a peroxy unit, i.e. . Bond breaking in the peroxy bridge, forming , can be used as a model for O 2 dissociation on an early transition metal oxide surface. The formation of ionic species was also investigated, and for all the oxide systems both cationic and anionic species were found to be stable. Ionization was also found to enhance the formation of cluster species.