Scientists’ discovery that π electron repulsion is more important than previously thought might change our understanding of conjugation. The effect is behind peculiar irregularities in bond lengths and resonance energies of conjugated molecules that our textbooks cannot explain.
Conjugated molecules like 1,3-pentadiene have π electrons that are delocalised across several bonds. Conjugation lowers a molecule’s overall energy and makes it more stable. However, a few years ago, researchers from Long Island University, US, claimed that conjugation could actually destabilise some molecules. They calculated cyanogen (NC–CN) to be less stable than its non-conjugated analogue ethylenediamine (H2NCH2–CH2NH2). Many researchers have tried to disprove this, but so far, no one has been able to give a simple explanation for these apparently counterintuitive results.
Read the full article in Chemistry World>>>
