4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid,3,3-dimethyl-7-oxo-6-[(phenylacetyl)- amino]- (2S,5R,6R)-,compounds,compd. with 2-(diethylamino)ethyl 4-aminobenzoate (1:1),mixt. with (2S,5R,6R)-3,3-dimethyl-7-oxo-6- [(phenylacetyl)amino]-4-thia-1-azab