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

Yukana Terasawa; Takashi Ohhara; Sota Sato; Satoshi Yoshida; Toru Asahi

doi:10.1107/S2056989022000858

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

Acta Crystallogr E Crystallogr Commun. 2022 Feb 8;78(Pt 3):306-312. doi: 10.1107/S2056989022000858. eCollection 2022 Feb 1.

Authors

Yukana Terasawa¹, Takashi Ohhara², Sota Sato³, Satoshi Yoshida⁴, Toru Asahi^{5

6}

Affiliations

¹ School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan.
² J-PARC Center, Japan Atomic Energy Agency, Shirakata 2-4, Tokai, Ibaraki, 319-1195, Japan.
³ Integrated Molecular Structure Analysis Laboratory, Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
⁴ Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
⁵ Faculty of Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan.
⁶ Research Organization for Nano & Life Innovation, Waseda University, 513 Wasedatsurumaki-cho, Shinjuku-ku, Tokyo, 162-0041, Japan.

Abstract

Precise single-crystal structure analyses of the title compound, bis-(glycinium) sulfate-glycine (1/1), 2C₂H₆NO₂ ⁺·SO₄ ^2-·C₂H₅NO₂ (or C₆H₁₇N₃O₁₀S), non-deuterated 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 mol-ecule that is associated with the ferroelectric behaviour of HTGS, O-H = 1.070 (3), H⋯O = 1.408 (3) [δ = 0.338 (4)], O⋯O = 2.4777 (15) Å and O-H⋯O = 179.0 (4)°, which is in good agreement with previous studies. Two reasonable structures for the same three atoms were refined for the 298 K dataset. One is a single-minimum potential-energy model, with O-H = 1.090 (12), H⋯O = 1.361 (12) [δ = 0.271 (17)], O⋯O = 2.450 (7) Å and O-H⋯O = 179.2 (10)°, 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 (8) and 0.124 (8): for the major occupancy component, O-H = 1.065 (12), H⋯O = 1.387 (12), O⋯O = 2.451 (7) Å and O-H⋯O = 178.2 (11)° and for the minor component, O-H = 1.06 (4), H⋯O = 1.41 (4), O⋯O = 2.451 (7) Å and O-H⋯O = 166 (2)°. These models did not show any significant differences in R factors. In addition, the unit-cell parameters and other structural parameters of HTGS did not show any major differences compared to those of partially deuterated TGS and fully deuterated TGS for both 20 K and 298 K.

Keywords: crystal structure; hydrogen atom; neutron diffraction; triglycine sulfate.

Grants and funding

This work was funded by Mitsubishi Materials Corporation grant AXA30Z001000; Waseda University Grants for Special Research Projects grant BARD01107201.