New Co(II) complexes of 5-nitroorotate with imidazole or N-methylimidazole co-ligands: Crystal and molecular structures, vibrational spectra and antimicrobial activities

Two novel Co(II) complexes of 5-nitroorotate with imidazole (ImH), [Co(5-NO₂HOr)(H₂O)₂(ImH)₂] (1) and N-methylimidazole (N-MeIm), [Co(5-NO₂HOr)(H₂O)₂(N-MeIm)₂] (2) have been synthesized and characterized by single crystal X-ray diffraction, PXRD, FT-IR and Raman spectroscopy, as well as elemental and thermal analyses. Both complexes crystallize in the monoclinic system (space group P2₁/c). The cobalt(II) ion is chelated by the 5-nitroorotate dianion through the carboxylate oxygen (O1) and the deprotonated pyrimidine nitrogen (N1) atoms. Two monodentate co-ligands, (ImH) in (1) or (N-MeIm) in (2), and two water molecules in cis conformation complete a distorted octahedral coordination sphere. Strong intermolecular O–H···O and N–H···O hydrogen bonds as well as weak N–O···π and C–H···π interactions, promote the crystal cohesion. The Hirshfeld surface analysis has been performed. Detailed assignment of the characteristic bands in the IR and Raman spectra, along with the thermogravimetric studies, have provided further evidence for the nature of bonding in these compounds. Additionally, both complexes have been investigated in vitro for their activity against selected bacteria: Gram-negative (E. coli ATCC 11229, P. aeruginosa ATCC 27853), Gram-positive (S. aureus ATCC 6538), and yeast (C. albicans ATCC 10231) under aerobic conditions. Moreover, their activity against bacteria that can constitute pathogens (E. coli ATCC 11229) or the probiotic strain (L. rhamnosus GG) has been tested under anaerobic conditions.