Magnetic and Mössbauer investigations of NN-disubstituted bis(dithiocarbamato)iron(II) complexes

Abstract

Bis(dithiocarbamato)iron(II) complexes [{Fe(S₂CNR₂)₂}_n] have been found to form two classes. With R = Et, Prⁿ, or Buⁿ, isomorphous relations with copper(II) complexes of known structure show that the complexes are dimers containing square-pyramidal iron. Considerable antiferromagnetic interaction is present, and the chemical isomer shifts and reflectance spectra are characteristic of high-spin Fe^II. Very large quadrupole splittings (ca. 4.2 mm s^–1) have been obtained. These complexes exhibit clean quadrupole doublets at 4.2 K consistent with diamagnetic ground states as expected for dimers. This is confirmed by the behaviour in an applied field. When R = Me or R₂= C₄H₈ no isomorphous relations have been found, but polymeric octahedral structures are suggested by the smaller quadrupole splitting (ca. 2.5 mm s^–1), weaker antiferromagnetism, reflectance spectra indicating less distortion, and the complex magnetic-hyperfine splitting at 4.2 K in zero field.