A case of breakdown of the Pauling bond order concept

Abstract

According to the Pauling bond orders, the lengths of the rung carbon-carbon bonds along the central hexagonal chain in chevron-type benzenoid molecules are monotonically changed. The calculated bond lengths obtained at the B3LYP/6-311G(d,p) level of theory show that this regularity holds only for the first few members of the chevron homologous series. In the case of higher members of the series, the predictions of the Pauling bond orders are false. This indicates that the Pauling bond orders are not generally applicable for the prediction of bond lengths.