Does the Electronic Structure of Möbius Annulenes Follow Heilbronner’s Ideas?

It is shown, on the example of the monocyclic cyclononatetraenyl cation, C9H9+, that the fully-variational optimization of modern ab initio wavefunctions based on spin-coupled generalized valence bond (SCGVB) theory vindicates, in a surprising level of detail, essential features of Heilbronner’s ideas for the electronic structure of Möbius annulenes such as the arrangement of overlapping carbon 2p atomic orbitals along a Möbius strip, leading to a phase inversion between the first and last orbitals. In the SCGVB description, the aromaticity of this Möbius system with eight pi electrons follows from the extensive resonance between VB structures.