Diradical

Not to be confused with biradical.

In chemistry, a diradical is a molecular species with two electrons occupying molecular orbitals (MOs) which are degenerate.[1][2] The term "diradical" is mainly used to describe organic compounds, where most diradicals are extremely reactive and non-Kekulé molecules that are rarely isolated. Diradicals are even-electron molecules but have one fewer bond than the number permitted by the octet rule.

Examples of diradical species can also be found in coordination chemistry, for example among bis(1,2-dithiolene) metal complexes.[3][4]

  1. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Diradicals". doi:10.1351/goldbook.D01765
  2. ^ Abe M (September 2013). "Diradicals". Chemical Reviews. 113 (9): 7011–7088. doi:10.1021/cr400056a. PMID 23883325.
  3. ^ Aragoni MC, Caltagirone C, Lippolis V, Podda E, Slawin AM, Woollins JD, et al. (December 2020). "Diradical Character of Neutral Heteroleptic Bis(1,2-dithiolene) Metal Complexes: Case Study of [Pd(Me2timdt)(mnt)] (Me2timdt=1,3-Dimethyl-2,4,5-trithioxoimidazolidine; mnt2-=1,2-Dicyano-1,2-ethylenedithiolate)". Inorganic Chemistry. 59 (23): 17385–17401. doi:10.1021/acs.inorgchem.0c02696. PMC 7735710. PMID 33185438.
  4. ^ Ray K, Weyhermüller T, Neese F, Wieghardt K (July 2005). "Electronic structure of square planar bis(benzene-1,2-dithiolato)metal complexes [M(L)(2)](z) (z=2-, 1-, 0; M=Ni, Pd, Pt, Cu, Au): an experimental, density functional, and correlated ab initio study". Inorganic Chemistry. 44 (15): 5345–5360. doi:10.1021/ic0507565. PMID 16022533.