CRYSTAL AND MOLECULAR-STRUCTURE OF THE PYROELECTRIC PHASE OF TGS AT 150-K

Single crystals of triglycine sulphate in the pyroelectric phase were crystallised from an aqueous solution of glycine and sulphamic acid. The crystals are monoclinic with the cell dimensions a = 5.6922(9) angstrom, b = 12.610(3) angstrom, c = 9.164(2) angstrom, beta = 105.33(1)-degrees, space group P2(1) and Z = 2. Least-squares refinement using 2870 X-ray (MoK-alpha) reflections (collected at 150 K) has led to an R-factor of 0.025 giving e.s.d. in bond lengths and angles of 0.002 angstrom and 0.2-degrees, respectively. Two of the three glycine molecules are protonated and the third exists in the zwitterionic state. The hydrogen bonding scheme includes two bifurcated bonds. The shortest O - H...O hydrogen bond has a length of 2.481(2) angstrom.