Construction of Meldonium (3-(1,1,1-Trimethylhydrazin-1-ium-2-yl)propanoate) Crystals: An X-ray View

Zwitter-ions of 3-(1,1,1-trimethylhydrazin-1-ium-2-yl)propanoate make head-to-tail dimers stabilized by N–H⋯O bonds; hydrogen bonding via water molecules results in an infinite chain (monohydrate, 1 ) or in a 3D network (dihydrate, 2 ). Hydrogen bonds in protonated form (2-(2-carboxyethyl)-1,1,1-trimethylhydrazinium) create an infinite chain (chloride, 3 ) or a 2D network (fumarate, 4 ). All these crystals are stabilized by weak C–H⋯A interactions. The crystallographic parameters at − 100 °C are as follows: 1 : triclinic, space group P 1 - ; a, b, c (Å): 7.3360(5), 8.0667(5), 8.9416(6); α = 99.752(4), β = 112.665(4), γ = 107.300(4)°,V = 441.32(5) Å 3 , Z = 2; 2 : monoclinic, space group P 2 1 / c; a, b, c (Å): 6.8854(4), 11.2483(7), 12.8254(8), β = 105.339(2) °, V = 957.93(10) Å 3 , Z = 4; 3 : monoclinic, space group P 2 1 / n; a, b, c (Å): 7.3625(4), 12.6486(7), 10.5211(6), β = 103.583(2)°, V = 952.38(9) Å 3 , Z = 4; 4 : monoclinic, space group P 2 1 / c; a, b, c (Å): 6.3669(6), 29.516(3), 6.8145(7), β = 91.009(5) °, V = 1280.4(2) Å 3 , Z = 4. Structure 2 is practically identical to that already measured at room temperature. Graphical Abstract In crystal state, zwitter-ions and protonated cations of meldonium are assembled via networks of hydrogen bonds