The First Lanthanide Complexes with a Redox-Active Sulfur Diimide Ligand: Synthesis and Characterization of [LnCp*2(RN=)2S], Ln=Sm, Eu, Yb; R=SiMe3

The first lanthanide complexes with a redox-active sulphur diimide ligand, [LnCp*2(Me3SiN=)2S] (Ln = Sm, Eu, Yb; Cp* = η5-C5Me5), are reported. The complexes were synthesized using [LnCp*2(THF)2] and (Me3SiN=)2S and have been thoroughly characterized by single-crystal X-ray diffraction, EPR spectroscopy, UV-Vis-NIR electronic absorption spectroscopy and SQUID magnetometry. The results, as interpreted by CASSCF/SOC-RASSI calculations providing a non-perturbative treatment of spin-orbit coupling, indicate that these paramagnetic complexes are best described as Ln3+ and [(Me3SiN=)2S]-* adducts. As such, these complexes contain the first isolated and structurally characterized acyclic [(RN=)2S]-* radical anions.