The Crystal and Molecular Structures of 5, -(+)-2, 2-Diphenylcyclopropanecarboxylic Acid and of R-(+)-2, 2-Diphenyl-l-methylcyclopropanecarboxylic Acid. A Study of the Environments of Gas-Solid Reactions That Exhibit Anisotropic Behavior

The crystal structures of S-(+)-2, 2-diphenylcyclopropanecarboxylic acid (I) and of R-(+)-2, 2-diphenyl-l-methyl-cyclopropanecarboxylic acid (II) have been determined to examine the environment of some gas-solid reactions. The crystals of [are monoclinic, a = 14.657(5), b = 6.238(2), c = 7.967(3) Å and β = 117° 15'(2'); there are two molecules of I in the space group P21. The structure was refined to an R factor of 0.043 on 1066 independent nonzero reflections. The crystals of II are orthorhombic, a = 18.199(5), b = 6.309(1), and c = 11.796(2) Å there are four molecules in the space group P212121. The structure has been refined to an R factor of 0.037 on 1261 independent nonzero reflections. The molecular structures of I and Il are very similar and the bond lengths in the cyclopropane ring show the influence of the exocyclic unsaturated substituents. Both structures exhibit linear chains or catemers formed by hydrogen bonding of the carboxylic acid groups along the b direction. In the crystal of I the b axis is polar and all the chains run in the same direction, whereas in II chains run in alternate directions along b. In both structures, the polar groups in the chains are well insulated from these groups in adjacent chains by nonpolar hydrocarbon groups, thus explaining the observed ditropic attack of ammonia gas on single crystals of I and II.