Cyclooctatetraenide anion explained

In chemistry, the cyclooctatetraenide anion or cyclooctatetraenide, more precisely cyclooctatetraenediide, is an aromatic species with a formula of [C₈H₈]^2- and abbreviated as COT^2−. 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.

The structure is a planar symmetric octagon stabilized by resonance, meaning each atom bears a charge of -. 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 salts

name	formula	CAS	remarks	references
Samarium(II) cyclooctatetraenide	Sm(C8H8)			^[2]
Dipotassium samarium(II) cyclooctatetraenide	K2Sm(C8H8)2
Neodymium cyclooctatetraenide	Nd(C8H8)2
Terbium cyclooctatetraenide	Tb(C8H8)2
	(Pa(C8H8)2)
	(Th(C8H8)2)
Uranocene	U(C8H8)2
	(Np(C8H8)2)
	(Pu(C8H8)2)
Cerocene	Ce^3+(C8H8^1.5-)2	37205-27-9		^[3]

See also

• Tropylium ion
• Cyclopentadienyl anion

Notes and References

1. Jug . Karl . Aromaticity in unusual heteropolar monocyclic rings with (4n + 2) π electrons . The Journal of Organic Chemistry . November 1984 . 49 . 23 . 4475–4478 . 10.1021/jo00197a029.
2. Wayda . Andrea L. . Cheng . Suzanne . Mukerji . Ishita . Cyclooctatetraenide derivatives of divalent samarium . Journal of Organometallic Chemistry . August 1987 . 330 . 3 . C17–C19 . 10.1016/S0022-328X(00)99059-4.
3. Marc D. Walter, Corwin H. Booth, Wayne W. Lukens, and Richard A. Andersen. Organometallics 2009, 28, 3, 698–707.