cyclooctatetraenide anion

{{Short description|Ion}}

{{Chembox

|ImageFile = Cyclooctatetraenide.svg

|ImageSize = 150px

|PIN = Cyclooctatetraenediide

|Section1 = {{Chembox Identifiers

| CASNo = 34510-09-3

| CASNo_Ref = {{Cascite|correct|CAS}}

| StdInChI=1S/C8H8/c1-2-4-6-8-7-5-3-1/h1-8H/q-2

| StdInChIKey=GSYKYIXVPVFJRF-UHFFFAOYSA-N

| SMILES = c1=c[cH-]c=c[cH-]c=c1

}}

|Section2 = {{Chembox Properties

|Formula = C₈H₈²⁻

|MolarMass = 104.15 g/mol

}}

}}

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.

The structure is a planar symmetric octagon stabilized by resonance, meaning each atom bears a charge of −{{sfrac|4}}. The length of the bond between carbon atoms is 1.432 Å. There are 10 π electrons.{{cite journal |last1=Jug |first1=Karl |title=Aromaticity in unusual heteropolar monocyclic rings with (4n + 2) π electrons |journal=The Journal of Organic Chemistry |date=November 1984 |volume=49 |issue=23 |pages=4475–4478 |doi=10.1021/jo00197a029}} The structure can serve as a ligand with various metals.