Quantum chemical calculations were performed to understand the formation of nanoscale cage clusters based on uranyl ions. We investigated the uranyl-peroxide-uranyl interaction and compared the geometries of clusters with and without such interactions. We show that a covalent interaction along the U-O-peroxo bonds causes the U-O-2-U dihedral angle to be bent, and it is this inherent bending of the configuration that encourages curvature and cage cluster formation. The U-O-2-U dihedral angle of the peroxo bridge is tuned by the size or electronegativity of the counterion present.