The crystal structure of triglycine sulfate†

Abstract

The structure of the ferro electric phase of Triglycine Sulfate has been refined from neutron diffraction data. The hydrogen bonding scheme proposed by Hoshino, Okaya and Pepinsky2 has been confirmed. The short hydrogen bond between glycine II and glycinium III that has been postulated to cause the transition has been found to have an O-O distance of 2.50 Å with the hydrogen atom 1.1 Å from the glycinium III ion. The glycinium I ion contains an ammonium group which moves about 1 Å in the transition. This group is 0.4 Å out of the plane of the carboxyl group. A possible transition mechanism is discussed.