The molecule is a monocarboxylic acid anion resulting from the deprotonation of the carboxy group of O-formylcefamandole. It is a conjugate base of an O-formylcefamandole.
(6R,7R)-7-[[(2R)-2-formyloxy-2-phenylacetyl]amino]-3-[(1-methyltetrazol-5-yl)sulfanylmethyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate