A cyclooctadiene (sometimes abbreviated COD) is a cyclic diene with the formula C8H12. Focusing only on cis derivatives, four isomers are possible: 1,2, which is an allene, 1,3-, 1,4-, and 1,5-. Commonly encountered isomers are 1,3-cyclooctadiene and 1,5-cyclooctadiene, which is used as a ligand for transition metals. ...