Synthesis, structure and Mössbauer characterization of polymeric iron(II) complexes with bidentate thiourea ligands

Complexes of FeCl2 with the known bis(3-methyl-2-thione-imidazolyl)methane (L1) and the new bis(3-tert-butyl-2-thione-imidazolyl)methane (L2) are reported. For both [L1FeCl2]n (3) and [L2FeCl2]n (4) X-ray crystallography reveals that 1D-polymeric chain structures are present in the solid state, with the two mercaptoimidazolyl units of L1 and L2 coordinating to different metal ions. Complexes 3 and 4 are further characterized by Mössbauer spectroscopy and SQUID magnetometry. NMR spectroscopy suggests that the complexes largely dissociate in polar solvents. X-ray structures of L2 and its precursor bis(imidazolium) salt are also reported.

Graphical abstractIn the solid state, labile bidentate bis(mercaptoimidazolyl)methanes do not act as chelating ligands towards FeCl2 but form 1D-polymeric chain structures with four-coordinate iron(II) that have been characterized by X-ray crystallography, SQUID measurements and a variety of spectroscopic methods.Figure optionsDownload full-size imageDownload as PowerPoint slide