[C5Li5]Znn[C5Li5] (n = 2-8): Novel sandwich complexes containing -Zn-Zn- chain

A density functional theory investigation on sandwich-type D5 [C5Li5]Znn[C5Li5] (n = 2-8) complexes containing -Zn-Zn- chain has been performed in this work at B3LYP/6-311+G(d) level. The Znn2+ sandwich complexes with D5 symmetry are all true minima on the potential energy surface. NBO analyses for the series of complexes reveal that the Zn-Zn bond is a weak σ covalent bond. The -Zn-Zn- chain plays a dominant role in the stability of the series of complexes. The C-C bond length in these complexes is slightly elongated with respect to that in C5Li5-, the NICS computed with GIAO-B3LYP/6-311+G(d) indicates that the C5Li5- rings in the series of complexes are aromatic. These novel complexes turn out to be strongly thermodynamically favored in the gas phases and may be targeted in future experiments to expand the structural domain of sandwich-type complexes.