Knowledge Bank

In a recent paper on the Symmetry Classification and Selection Rules for Some Electron Donor-acceptor (DA) Complexes (J. Am. Chem. Soc., 92 (June, 1970)), examples of structure and spectra of some $\pi$-molecular complexes are discussed in view of point group requirements ($C2$, $C2v$, etc.) An extension of this approach to the structure of $\pi$-molecular complexes will be presented where all the $\pi$-nodal planes of the $D+$, and $A-$ radical-ions are considered and not just the nodal planes that happen to coincide with symmetry planes of the molecule. This allows for a more descriptive and more inclusive study of DA complexes and suggests a path by which the structure of biologically significant molecular complexes might be approached.