TOPOCHEMICAL STUDIES .14. STRUCTURES OF 3,3'-DIBROMOTRUXINIC ACID WATER ACETIC-ACID (0.5/0.25) SOLVATE AND 3,3'-DICHLOROTRUXINIC ACID WATER ACETIC-ACID (0.5/0.25) SOLVATE

3,4-Bis(3-bromophenyl)-1,2-cyclobutanedicarboxylic acid water-acetic acid (0.5/0.25) solvate (1), C18H14Br2O(4.)0.5H2O.0.25C2H4O2, M(r) = 478.12, triclinic, P1BAR, a = 8.670 (1), b = 14.253 (1), c = 8.1895 (8) angstrom, alpha = 104.567 (8), beta = 102.545 (8), gamma = 79.379 (9)-degrees, V = 947.0 (2) angstrom 3, Z = 2, D(m) = 1.68, D(x) = 1.677 Mg m-3, mu = 5.70 mm-1, F(000) = 474, final R = 0.071 for 2819 non-zero reflections. 3,4-Bis(3-chlorophenyl)-1,2-cyclobutanedicarboxylic acid water-acetic acid (0.5/0.25) solvate (2), C18H14Cl2O(4.)0.5H2O.0.25C2H4O2, M(r) = 389.12, triclinic, P1BAR, alpha = 8.634 (1), b = 14.228 (2), c = 8.001 (1) angstrom, alpha = 103.49 (1), beta = 102.91 (1), gamma = 79.43 (1)-degrees, V = 922.6 (2) angstrom 3, Z = 2, D(m) = 1.39, D(x) = 1.401 Mg m-3, mu = 3.44 mm-1, F(000) = 402, final R = 0.057 for 2643 non-zero reflections. T = 295 K, Cu K-alpha, lambda = 1.54178 angstrom. The present compounds are the photodimers of 3-bromo- and 3-chlorocinnamic acids. The crystals of (1) and (2) are isomorphous with each other. These two dimers have beta-truxinic acid type structures as expected from the crystal structures of the monomers. The solvent molecules in these crystals are disordered around 1BAR.