Resonance



  • What are the conditions for resonance to take place in a compound?



  • @Tera-Deewana

    1.The compound should be represented by more
    than one correct Lewis dot structures.
    2.All the lewis structures must have same skeleton
    (basic layout of the principle chain) and the
    molecular formula too..
    3. The molecule should be planar.
    4. The resonating structures must have almost
    similar energies..
    5. There should be a closed conjugation of any sorts
    Pi sigma pi, pi sigma lone pair, pi sigma positive
    charge, anything..







  • @abhijeet-kumar which type of conjugation
    Is present in NO for resonance to take place?



  • @Tera-Deewana The most common bonding mode of nitric oxide is the terminal linear type (M−NO). Alternatively, nitric oxide can serve as a one-electron pseudohalide. The nature of the NO-bond in the N-oxide group was investigated by means of combined theoretical calculations . The N-O bond in the N-oxide group should be classified as the NO donating bond with an important contribution of ON back-donation (of the π-electron type, when available). A detailed bonding analysis performed by means of natural resonance theory indicates that the N→O bond is of an order of magnitude clearly greater than 1. In addition, the stability of the N→O bond in various N-oxides was estimated. The analyses of the hydrogen- and halogen-bonded complexes of the N-oxides reveal strong Lewis basicity of the N-oxide group.
    Example: Moreover, in pyridine-N-oxide, the electron-withdrawing -NO2 group additionally stabilizes the N→O bond, whereas the opposite effect can be observed for the electron-donating-NH2 substituent. This is due to a substituent effect on the π-type ON back-donation. As a result, the oxygen atom in pyridine-N-oxide may change its availability during intermolecular interaction formation, as revealed in the interaction energy, which changes by about half of the estimated total interaction energy.


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