“…[19][20][21][22][23][24][25][26] In addition, the dimethylammonium tetrabromozincate(II), [NH 2 (CH 3 ) 2 ] 2 ZnBr 4 , crystal is a member of the [NH 2 (CH 3 ) 2 ] 2 MX 4 family, which belongs to a group of A 2 MX 4 types, where A + is a univalent cation, M 2+ is a divalent transition metal, and X is a halogen. [27][28][29][30][31][32][33][34][35][36] These crystals undergo several structural phase transitions, oen associated with the ordering of hydrogen bonds and related changes in the molecular dynamics of the [NH 2 (CH 3 ) 2 ] + ions. The individual MX 4 tetrahedral anions in these materials are completely isolated and surrounded by organic [NH 2 (CH 3 ) 2 ] + cations.…”