CRYSTAL-STRUCTURE AT 110K OF (R)-1-PHENYLETHYLAMMONIUM HYDROGEN MALEATE-WATER (1 0.25), AND A STUDY OF THE CONFORMATION OF 1-PHENYLETHYLAMMONIUM IONS/

The title compound crystallizes in the orthorhombic space group C2 wit h a = 39.191(4), b = 5.624(2), c = 11247(2) Angstrom and beta = 95.750 (11)degrees, Z = 8. Using 3182 reflections the structure was refined t o R = 0.027 and R(w) = 0.032. A short asymmetric intramolecular hydrog en bond is observed in both crystallographically independent anions; t he two O-O distances are 2.42 and 2.44 Angstrom. One of the hydrogen m aleate ions displays a significant twist of the carboxylic groups rela tive to the double bond. The two (R)-1-phenylethylammonium ions are vi rtually identical. The water molecule links one of the cations to one of the anions. Based on a search of the Cambridge Structural Database the conformations of 1-phenylethylammonium ions in different salts hav e been investigated. This showed that three preferred orientations of the phenyl group exist for the ion.