Single-crystal structure analysis of non-deuterated triglycine sulfate by neutron diffraction at 20 and 298 K; A New disorder model for the 298 K structure

Terasawa, Yukana*; Ohara, Takashi   ; Sato, Sota*; Yoshida, Satoshi*; Asahi, Toru*

Precise single-crystal structure analyses of the title compound, nondeuterated triglycine sulfate (HTGS) at 20 K and 298 K were undertaken using time-of-flight neutron diffraction data. At 20 K for the O-H...O hydrogen bond between the glycinium cation and the zwitterionic, unprotonated glycine molecule that is associated with the ferroelectric behaviour of HTGS. Two reasonable structures for the same three atoms were refined for the 298 K dataset. One is a single-minimum potential-energy model, having the H atom with a large ellipticity along the bond path between the O atoms. The other is a double-minimum potential-energy model having two H atom sites with occupancies of 0.876 and 0.124.