The geometries of both the small and large (in the infinite chain limit) Brooker cations C2n−1H2n+3N+2are studied using a &pgr;‐electron Hamiltonian designed to reproduce AM1 results. Ions with ≤15 CH units are predicted to be symmetrical (C2vwith a soliton defect at the chain centre; larger ions are predicted to be planar (Cs) but have a localized defect at one end of the molecular and a very low energy transition state. While the Csstructures could be useful in molecular switches, here we concentrate on the usefullness of the C2&ngr;structures as molecular wires. The Brooker ion C2&ngr;structures appear qualitatively differently from the analogous polyene anions for chain lengths less than 40 CH units because the end effects in the Brooker ions are stronger and of longer range than in the polyene ions. For chain lengths greater than this, the C2&ngr;structures of both the polyene ions and the Brooker ions resembles those of negative‐defect and positive‐defect trans‐polyacetylene, respectively, owing to the onset of Peierls distortion. All of the unit positive charge is shown to reside on the central region of the C2&ngr;structures of large Brooker ions. The band gap in the infinite C2&ngr;Brooker ion is shown to be about half that of polyacetylene, and the lowest singlet absorption frequency is shown to be non‐zero. The rate constant for electron transfer through symmetrical Brooker ion bridges is predicted to be larger than that through the related even‐membered bridges; symmetry breaking is predicted to inhibit direct electron transfer and to facilitate soliton transport.