The molecule is the anion resulting from the removal of a proton from the carboxylic acid group of cephalexin. It is a conjugate base of a cephalexin.
(6R,7R)-7-[[(2R)-2-amino-2-phenylacetyl]amino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate