Odd-memberedC2? ?-cyclic mono- and dications with internal cross-linking. A H�ckel approach for the description of antiaromaticity

With the Hückel method using a bond-length-dependent coupling (β), a description is given for the various C2ν geometries for odd-membered cyclic 4n π electrons under cross-linking, so we arrive at a more general conclusion with respect to their antiaromatic behavior. Model systems are introduced to illustrate this quantum-chemical approach. As an interesting spin-off of these model systems, we may conclude that the tetrahedral configuration for saturated carbon is not the absolute geometry.