Synthesis, spectroscopic and redox behaviour of copper(II) complexes with quinquedentate thiaaza ligands
摘要:
Three potentially quinquedentate ligands, 1,11-diamino-6-oxa-3,9-dithiaundecane (LO), 1,6,11-triaza-3,9-dithiaundecane (LN), 1,11-diamino-3,6,9-trithiaundecane (LS) and their quadridentate analogue 1,11-diamine-3,9-dithiaundecane (LC) were prepared. Their copper(II) complexes of composition CuL(ClO4)2 have been isolated for the quinquedentate ligands, whereas for LC the dimeric complex Cu2(LC)3(ClO4)2 was the main product. ESR spectroscopy showed that the copper(II) complex with LO has rhombic symmetry, whereas the complexes with LN and LS are tetragonal, and the dimeric LC complex exhibits a weak Cu(II)-Cu(II) interaction. The cyclic voltammograms of the complexes with the quinquedentate ligands show a negative potential shift in comparison with the complex with the tetradentate ligand LC. Under CO, the E1/2 value for Cu(LS)(ClO4)2 shifts anodically by 50 mV due to formation of [Cu(LS)(CO)]+.