The crystal structure of the 5-oxotricyclo[2.2.1.02,6]heptane-3-carboxylic acid stereoisomer: an exercise in the application of a new automatic phasing procedure

rac-3-exo-Ammonio-7-anti-carboxytricyclo[2.2.1.0.2,6]heptane-3-endo-carboxylate monohydrate

The racemic title compound, C₉H₁₁NO₄·H₂O, a tricyclic rearranged amino­norbornane dicarb­oxy­lic acid, is a conformationally rigid analogue of glutamic acid and exists as an ammonium-carboxyl­ate zwitterion, with the bridghead carb­oxy­lic acid group anti-related. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds involving the ammonium, carb­oxy­lic acid and water donor groups with both water and carboxyl O-atom acceptors give a three-dimensional framework structure.