Baird's rule

In organic chemistry, Baird's rule estimates whether a lowest triplet state of planar ring molecule will have aromatic properties. The quantum mechanical basis for its formulation was first worked out by physical chemist N. Colin Baird in 1972.[1][2]

A lowest triplet state of cyclic ring molecule follows Baird's rule when the number of its π-electrons equals 4n where n is any positive integer. However, in most cases the lowest triplet state of cyclic ring has higher energy then the lowest singlet state of cyclic ring due to Jahn–Teller effect.

See also

References

  1. ↑ Baird, N. Colin (1972), "Quantum organic photochemistry. II. Resonance and aromaticity in the lowest 3ππ* state of cyclic hydrocarbons", Journal of the American Chemical Society (07/12), doi:10.1021/ja00769a025
  2. ↑ Ottosson, Henrik (2012), "Organic photochemistry: Exciting excited-state aromaticity", Nature Chemistry 4: 969–971, doi:10.1038/nchem.1518
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