Abstract
The crystal structure of cis-3-carboxylic acid-1,2,3,4-tetrahydroharmane dihydrate, C13H13N2O2.cntdot.2H2O, a putative ligand of the benzodiazepine receptor, is reported. The space group is P21/c with .alpha. = 14.850(4), b = 6.560(3), c = 14.746(4) .ANG. and .beta. = 117.411(8).degree., Z = 4. The molecule crystallizes as a zwitterion with the unsaturated ring in a half-chair conformation. H bonding to the water molecules included in the lattice determines the molecular packing arrangment.