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.