Crystal structure of diethylammonium p-aminobenzoate (Nevanide)

The crystal structure of Nevanide (diethylammonium p-aminobenzoate) has bee n determined and refined to a residual R 0.055 for 2797 observed reflection s. Crystals are monoclinic, space group C 2/c, with 32 ion pairs in a cell with dimensions a 29.510(6), b 17.150(1), c 20.473(5) Angstrom, beta 115.15 3(9)degrees. The structure is made up of a network of hydrogen-bonded ions; in this network the 4-aminobenzoate anions form a primary cyclic tetramer unit in which the amine groups of two residues are linked tail to tail thro ugh hydrogen bonds to single carboxylate oxygens of the other two residues. All oxygens are then linked peripherally to layers of diethylammonium cati ons by strong hydrogen bonding, with all possible hydrogen bonding sites ut ilized, giving a three-dimensional network array.