The molecule is the penicilloate(2-) species that is the dianion formed from benzylpenicilloic acid by deprotonation of both carboxy groups. It is the major microspecies present at pH 7.3. It is a conjugate base of a benzylpenicilloic acid.
(2R,4S)-2-[(R)-carboxylato-[(2-phenylacetyl)amino]methyl]-5,5-dimethyl-1,3-thiazolidine-4-carboxylate