Creatininium cinnamate

Synthesis, crystal structure determination and Hirshfeld surface analysis of three new salt forms of creatinine with hydrobromic acid, 3-aminobenzoic acid and 3,5-dinitrobenzoic acid

Creatinine, a biologically important compound, is used to analyze kidney function and kidney diseases in the human body. The salt form of creatinine is used in the formation of drug materials like anti-HIV, antifungal, antiprotozoal, antiviral and antitumour compounds. Here we report the solid-state structures of three new crystalline salts, namely, creatininium (2-amino-1-methyl-4-oxo-4,5-dihydro-1H-imidazol-3-ium) bromide, C4H8N3O+·Br−, (I), creatininium 3-aminobenzoate, C4H8N3O+·C7H6NO2 −, (II), and creatininium 3,5-dinitrobenzoate, C4H8N3O+·C7H3N2O6 −, (III). These salts have been synthesized and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis. The structural chemistry of salts (I)–(III) and their crystal packing are discussed in detail. The primary interaction between the creatinine cation and the acid anion in the three salts is N—H...Br/O hydrogen bonds. In salt (I), the creatinine cation and bromide anion are connected through a pair of N—H...Br hydrogen bonds forming R 4 2(8) and R 4 2(12) ring motifs. In salts (II) and (III), the creatinine cation interacts with the corresponding anion via a pair of N—H...O hydrogen bonds. The crystal structure is further stabilized by C—H...O and O—H...O hydrogen bonds with the ring motifs R 2 2(8), R 2 1(7) and R 2 1(6). Furthermore, the crystal structures are stabilized by π–π, C—H...π, C—O...π and N—O...π stacking interactions. The contributions made by each hydrogen bond in maintaining the crystal structure stability has been quantified by Hirshfeld surface analysis.

Creatininium 2-chloro-acetate

In the title compound (systematic name: 2-amino-1-methyl-4-oxo-4,5-dihydro-1H-imidazol-3-ium 2-chloro­acetate), C₄H₈N₃O⁺·C₂H₂ClO₂⁻, the mol­ecular aggregations are stabil­ized through classical (N—H⋯O) and non-classical (C—H⋯O and C—H⋯N) hydrogen-bonding inter­actions. The cations are linked to the anions, forming ion pairs through two N—H⋯O bonds that produce characteristic R₂²(8) ring motifs. These cation–anion pairs are connected through another N—H⋯O hydrogen bond, leading to an R₄²(8) ring motif. Further weak C—H⋯N inter­actions link the mol­ecules along the a axis, while other C—H⋯O inter­actions generate zigzag chains extending along b.

Creatinium hydrogen oxalate

The crystal structure of the title compound, C(4)H(10)N(3)O(2) (+)·C(2)HO(4) (-), is stabilized by N-H⋯O and O-H⋯O hydrogen bonds. The anions are connected by an O-H⋯O hydrogen bond, leading to C(5) chain extending along c axis. The cations are dimerized around the corners of the unit cell, leading to an R(2) (2)(14) ring motif. This leads to a cationic mol-ecular aggregation at x = 0 or 1 and an anionic mol-ecular aggregation at x = 1/2.

Creatininium hydrogen maleate

In the title compound, C₄H₈N₃O⁺·C₄H₃O₄⁻, the cations and anions are linked through N—H⋯O hydrogen bonds making a ionic pair with an R₂²(8) ring motif. These ionic pairs are further connected through another N—H⋯O hydrogen bond, leading to an R₆⁶(16) ring motif around the inversion centres of the unit cell. These approximately planar aggregates are further connected through weak van der Waals inter­actions in the unit cell. The anions have a characteristic intra­molecular O—H⋯O hydrogen bond with a self-associated ring S(7) motif.