Supramolecular architectures in the salt trimethoprimium ferrocene‐1‐carboxylate and the cocrystal 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–ferrocene‐1‐carboxylic acid (1/1)

• Published in: Acta crystallographica. Section C, Crystal structure communications Crystal structure communications, 2017-09, Vol.73 (9), p.743-748
• Main Authors: Swinton Darious, Robert, Thomas Muthiah, Packianathan, Perdih, Franc
• Format: Article
• Language: English
• Subjects: Acids; Angles (geometry); antibacterial compound; Antibacterial materials; Carboxyl group; Carboxylic acids; cocrystal; Crystal structure; eclipsed; ferrocene‐1‐carboxylic acid; Hydrogen; Hydrogen bonds; Iron; Molecular biology; Salt; Salts; staggered; supramolecular architectures; Torsion; Trimethoprim; π–π stacking interactions
• ISSN: 2053-2296; 0108-2701; 2053-2296; 1600-5759
• DOI: 10.1107/S2053229617011913

In the salt trimethoprimium ferrocenecarboxylate [systematic name: 2,4‐diamino‐5‐(3,4,5‐trimethoxybenzyl)pyrimidin‐1‐ium ferrocene‐1‐carboxylate], (C14H19N4O3)[Fe(C5H5)(C6H4O2)], (I), of the antibacterial compound trimethoprim, the carboxylate group interacts with the protonated aminopyrimidine group of trimethoprim via two N—H…O hydrogen bonds, generating a robust R22(8) ring motif (heterosynthon). However, in the cocrystal 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–ferrocene‐1‐carboxylic acid (1/1), [Fe(C5H5)(C6H5O2)]·C6H8ClN3, (II), the carboxyl–aminopyrimidine interaction [R22(8) motif] is absent. The carboxyl group interacts with the pyrimidine ring via a single O—H…N hydrogen bond. The pyrimidine rings, however, form base pairs via a pair of N—H…N hydrogen bonds, generating an R22(8) supramolecular homosynthon. In salt (I), the unsubstituted cyclopentadienyl ring is disordered over two positions, with a refined site‐occupation ratio of 0.573 (10):0.427 (10). In this study, the two five‐membered cyclopentadienyl (Cp) rings of ferrocene are in a staggered conformation, as is evident from the C…Cg…Cg…C pseudo‐torsion angles, which are in the range 36.13–37.53° for (I) and 22.58–23.46° for (II). Regarding the Cp ring of the minor component in salt (I), the geometry of the ferrocene ring is in an eclipsed conformation, as is evident from the C…Cg…Cg…C pseudo‐torsion angles, which are in the range 79.26–80.94°. Both crystal structures are further stabilized by weak π–π interactions. A salt, trimethoprimium (TMP) ferrocene‐1‐carboxylate, and a cocrystal, 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine (ACDPY)–ferrocene‐1‐carboxylic acid (1/1), have been synthesized and characterized by single‐crystal X‐ray diffraction. The supramolecular architectures are generated by different hydrogen‐bonding interactions, and weak stacking interactions stabilize both crystal structures.