Lastly, when the bicyclopentane ring is substituted with two s-EWG's, a unifying depiction of dominant donor-acceptor interactions by NBO analysis (Figure , bottom) also accounts for the further decrease in C1•••C3 distance and would suggest that there are competing forces dictating bond elongation/contraction and charge distribution on the wings. 31b Theoretically, these push-pull effects would not result in the same structural trends observed for compounds like 3; in fact, this was found to be the case experimentally in structures 2, 7, 8, 9, and 17 (Figure 5, bottom).