Homodinuclear lanthanoid(III) dithiocarbamato complexes bridged by 2,2′-bipyrimidine: Syntheses, structures and spectroscopic properties

Abstract Four new homodinuclear lanthanoid(III) dithiocarbamato (RR′dtc−) complexes bridged by 2,2′-bipyrimidine (bpm) of the form [{Ln(RR′dtc)3}2(µ-bpm)] {Ln = Nd or Eu; RR′ = dimethyl- (Me2) or pyrrolidine- (pyr)} were prepared and their crystal structures and spectroscopic properties were characterized. The crystallographic studies revealed that all of the complexes possess a similar structural motif with an 8:8-coordination geometry, in which the bpm ligand bridges two LnIII centers in the κ2N1,1′:κ2N3,3′ mode and three RR′dtc− ligands coordinate to each LnIII center. The complexes exhibit weak but relatively sharp f–f transition bands in the absorption and magnetic circular dichroism (MCD) spectra recorded in the visible region. The MCD spectral studies demonstrated the magneto-optical behavior of the complexes. The spectral features of the dithiocarbamato complexes were distinctly different from those of their β-diketonato analogues, suggesting the coordination environment around the LnIII center influences the electronic structure and spectroscopic symmetry of the complexes in solution.