Crystal and molecular structure of 8-carboxy-1-hydroxy-2-oxobicyclo-[3,2,2]non-6-ene-9,4-carbolactone

Abstract

The structure of 8-carboxy-1-hydroxy-2-oxobicyclo[3,2,2]non-6-ene-9,4-carbolactone has been determined by a three-dimensional X-ray analysis. The monoclinic unit cell (space group P2₁/c) has dimensions a= 8·922, b= 8·801, c= 12·935 Å, and β= 92·85° for Z= 4. The structure was solved by centrosymmetric symbolic addition, and refined by least-squares calculations to R= 0·088 for 1121 reflections. The molecular structure is shown to be that of a racemic compound with two molecules of each enantiomer in the unit cell. The molecules occur as dimers which are strongly hydrogen bonded through the acid groups. The bicyclo[3,2,2]nonene ring system shows flattening of the three-carbon bridge.