Complexation of cyclohexadiene tricarbonyl iron with imidazolidine-2-thione. Crystal structural and antimicrobial activity studies of the tricarbonyl (1-4-η-5-N-imidazolidinio-2-thionecyclohexa-1,3-diene) iron labelled complex

Abstract

The reaction of imidazolidine-2-thione C3H6N2S with tricarbonyl (1-4-η-5-N-pyridiniocyclohexa-1,3-diene) iron tetrafluoroborate [C14H12NFe(CO)3]+ BF4−1 afforded a new iron complex tricarbonyl (1-4-η-5-N-imidazolidinio-2-thionecyclohexa-1,3-diene) iron of formula C9H11N2S Fe(CO)32. The imidazole ring was substituted by the metal-carbonyl unit [1-4-η-C6H7 Fe(CO)3]−. Labelled complex 2 was characterized by X-ray crystallography and by classical spectroscopic analysis (1H NMR and IR). There are two independent molecules [(C9H11N2S)Fe(CO)3] A and B in the asymmetric unit. The metal–ligand arrangement in A and B molecules is typical of 1,3-diene tricarbonyl iron complexes. The crystal packing, N–H⋯S and C–H⋯O hydrogen-bonding interactions stabilize the structure and build up chains parallel to [010]. Antimicrobial activity studies of the imidazolidine-2-thione and the labelled complex show that the iron complex 2 exhibits smaller antibacterial activity compared to the free ligand.