We thus questioned whether the electronic structure and distinct reactivity of cyclopropane, and other strained systems, could be understood through the models commonly used to describe their ground state bonding. The Coulson-Moffitt 'bent bonds' description, Walsh's (p+sp 2 ) rehybridization model, Dewar's s-aromaticity proposal, and Weinhold and Landis' geminal hyperconjugation model all suggest that the valence electrons of cyclopropane are not confined to individual C-C s bonds. Instead, these electrons delocalize in an analogous manner to an aromatic π system, in contrast to the typical localized C-C s bonds found in cyclobutane. This is illustrated by the higher dipole moment of chlorocyclobutane (2.20 D) compared to chlorocyclopropane (1.76 D), the latter being similar to that of chlorobenzene (1.60 D). While the importance of delocalization on the thermodynamic stability of systems containing conjugated π bonds (including aromatic rings) is universally accepted, its effect on bonding and reactivity in s frameworks, particularly in non-classically delocalized systems such as cyclopropane, has yet to be established.