5-[2-[3-Ethylbenzothiazol-2(3H)-ylidene]ethylidene]-4,4'-dioxo-2'-thioxo-Δ2,5'-bithiazolidine-3,3'-diacetic acid

5-[3-(carboxymethyl)-5-[(3-ethylbenzothiazol-2(3H)-ylidene)ethylidene]-4-oxothiazolidin-2-ylidene]-4-oxo-2-thioxothiazolidin-3-acetic acid