A new pyrimidinium tetrachloroferrate(III) salt with a low band gap: Hirshfeld surface analysis, crystal structure and physicochemical studies

The chemical preparation, characterization by single-crystal X-ray diffraction, elemental analysis and IR spectroscopy of the new Fe(III) complex (C5H7.50N3O)2[FeCl4] are reported. The Fe(III) cation is four-coordinated, in tetrahedral fashion, by four chlorine atoms. The [FeCl4]− tetrahedra are located parallel to the (a, b) plane at z = ¼ (2n + 1) between layers of organic cations (C5H7.50N3O)2+. The FeCl4 moieties are inserted between these planes by establishing N–H...Cl and C–H…Cl hydrogen bonds generated by amino and methyl groups as donors and Cl− anions as acceptors to form a three-dimensional network. The organic groups are linked together by N–H...N hydrogen bonds to form chains extending along the [110] direction. These chains are arranged in planes parallel to (a, b) at z = ½n. Intermolecular contacts on the Hirshfeld surface were investigated statistically. The most favored and stabilizing contacts are the strong (N–H…Cl−, N–H…N) hydrogen bonds as well as the weaker ones C–H…Cl−. The vibrational absorption bands were identified by infrared spectroscopy. Electronic properties such as HOMO and LUMO energies were also derived.