Oxalate
Oxalate (IUPAC: ethanedioate) is the dianion with the formula C2O42−, also written (COO)22−. Either name is often used for derivatives, such as salts of oxalic acid (for example disodium oxalate, (Na+)2C2O42−) or esters thereof (for example dimethyl oxalate, (CH3)2C2O4). Oxalate also forms coordination compounds where it is sometimes abbreviated as ox.
Read more about Oxalate.