Cyclooctatetraenide anion


In chemistry, the cyclooctatetraenide anion or cyclooctatetraenide, more precisely cyclooctatetraenediide, is an aromatic species with a formula of [C8H8]2− and abbreviated as COT2−. It is the dianion of cyclooctatetraene. Salts of the cyclooctatetraenide anion can be stable, e.g., Dipotassium cyclooctatetraenide or disodium cyclooctatetraenide. More complex coordination compounds are known as cyclooctatetraenide complexes, such as the actinocenes.

Cyclooctatetraenide anion
Preferred IUPAC name
  • 34510-09-3
3D model (JSmol)
  • Interactive image
  • c1=c[cH-]c=c[cH-]c=c1
Molar mass 104.15 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

The structure is a planar symmetric octagon stabilized by resonance, meaning each atom bears a charge of −1/4. The length of the bond between carbon atoms is 1.432 Å. There are 10 π electrons.[1] The structure can serve as a ligand with various metals.

List of saltsEdit

name formula CAS remarks references
Samarium(II) cyclooctatetraenide Sm(C8H8) [2]
Dipotassium samarium(II) cyclooctatetraenide K2Sm(C8H8)2 [2]
Neodymium cyclooctatetraenide Nd(C8H8)2
Terbium cyclooctatetraenide Tb(C8H8)2
Protactinocene (Pa(C8H8)2)
Thorocene (Th(C8H8)2)
Uranocene U(C8H8)2
Neptunocene (Np(C8H8)2)
Plutonocene (Pu(C8H8)2)

See alsoEdit


  1. ^ Jug, Karl (November 1984). "Aromaticity in unusual heteropolar monocyclic rings with (4n + 2) π electrons". The Journal of Organic Chemistry. 49 (23): 4475–4478. doi:10.1021/jo00197a029.
  2. ^ a b Wayda, Andrea L.; Cheng, Suzanne; Mukerji, Ishita (August 1987). "Cyclooctatetraenide derivatives of divalent samarium". Journal of Organometallic Chemistry. 330 (3): C17–C19. doi:10.1016/S0022-328X(00)99059-4.