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-HO 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-HA interactions. The crystallographic parameters at - 100 degrees C are as follows: 1: triclinic, space group P-1(-); a, b, c (angstrom): 7.3360(5), 8.0667(5), 8.9416(6); alpha=99.752(4), beta=112.665(4), gamma=107.300(4)degrees,V=441.32(5) angstrom(3), Z=2; 2: monoclinic, space group P2(1)/c; a, b, c (angstrom): 6.8854(4), 11.2483(7), 12.8254(8), beta=105.339(2) degrees, V=957.93(10) angstrom(3), Z=4; 3: monoclinic, space group P2(1)/n; a, b, c (angstrom): 7.3625(4), 12.6486(7), 10.5211(6), beta=103.583(2)degrees, V=952.38(9) angstrom(3), Z=4; 4: monoclinic, space group P2(1)/c; a, b, c (angstrom): 6.3669(6), 29.516(3), 6.8145(7), beta=91.009(5) degrees, V=1280.4(2) angstrom(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 [GRAPHICS] .