How Different are Electron-Rich and Electron-Deficient π Interactions?

The intermolecular interaction driven structural change is vital to molecular architecturing. In the Cambridge Structural Database (CSD), we find that the preference for geometrical conformations of electron-deficient π systems is different from those of electron-rich π systems. Indeed, ab initio calculations find that electron-deficient π ring systems should involve different structures and energetics, consistent with the CSD search, due to the electric multipole moments and the decrease in the spatial extent of π-electron density.