Metal sandwich and ion complexes in cyclacene nanobelts

Abstract

Cyclacene carbon nanobelts represent the last unsynthesized building blocks of carbon nanotubes and are the shortest possible hydrogen capped nanotubes of zigzag type. Recent theoretical predictions indicate that stable cyclacene isomers containing Dewar benzene derived structures may exist. The properties of the Hückel-[n]cyclacene nanobelt complexes containing alkali metal and halide ions (n = 5-8), with zero to two Dewar benzenoid structures present, and transition metal complexes (n = 6, 8) with zero and two Dewar structures present, have been calculated using density functional theory. The halides, alkali metals, and transition metals were initially placed centrally within the belt cavities, and binding interactions have been observed for both positive and negative ions. The most stable isomeric forms are found to change for several of the belt sizes, depending on which ions are present. Internal transition metal sandwich complexes with η6-haptic bonds are also indicated to form within the cyclacene belts containing two Dewar benzenoids.