Abstract
The free‐electron model for conjugated molecules is extended to a discussion of molecular complexes formed from conjugated molecules (π‐molecular complexes). The forces responsible for complex formation are identified as ``π‐delocalization'' forces. The stability and the absorption spectra of these complexes are discussed for a linear, one‐dimensional model. The influence of hydrostatic pressure on the position of the complex absorption spectrum is considered, and some predictions are made regarding the resulting shifts of various absorption peaks. The free‐electron model is compared with the models suggested by other workers, and good agreement is found in regard to the factors governing the formation and spectra of molecular complexes.