THE CRYSTAL-STRUCTURE OF BENZOYL-HISTIDINE MONOHYDRATE

The crystal structure of benzoyl-histidine monohydrate (BYLH hereafter ), C-13H-12N-3O-3. H2O was determined from three dimensional data of 3 012 independent reflections measured on a Enraf-Nonius (CAD4) single c rystal diffractometer. The compound crystallizes in the orthorhombic s pace group P2(1)2(1)2(1) with cell dimensions alpha = 7.102(1) angstro m, b = 13.783(3) angstrom, c = 14.160(4) angstrom, V = 1385.92 angstro m-3, F.W. = 277.28, F(000) = 584 Q(calc) = 1.32 g cm-3 and Z = 4. The structure was solved with direct methods. All positional and anisotrop ic thermal parameters were refined by full-matrix least-squares calcul ations. The final reliability factor was R = 0.040, while the weighted one was Rw = 0.034. The H atoms found in the difference Fourier map w ere refined isotropically. The compound consists of a histidine molecu le bound to a benzoyl group. There is also a cocrystallized water mole cule stabilized through a hydrogen bridge.The 5-membered ring of the h istidine has its tautomeric form, after the transfer of the H atom fro m the N(delta) to the N(epsilon) atom of the ring. There is an sp2 con formation around C6 while the conformation around C3 is that of sp3. T he histidine ring forms with the benzene ring a dihedral angle of 109. 8(1)-degree. All angle values and bond distances agree very well with the expected values in the literature.