Formation of Bimetallic Bis(dithiocarbamate) Macrocyclic Complexes

The work deals with the synthesis and characterisation of a range of dithiocarbamte ligands and their macrocyclic bis(dithiocarbamate) complexes. Multistep synthetic procedures were used to obtain ligands. This was based on the preparation of the Schiff-bases. Subsequently reduction of the Schiff-bases resulted in the formation of amine precursors that reacted with CS2 in presence of KOH to get the free ligands (L1-L4). On the other hand we were unable to isolate L5 and L6 and a one pot template reaction approach was implemented to obtain complexes. The reaction of the ligands with some metal ions resulted in the formation of macrocyclic complexes of general formula [MII(Ln)]2 (M= Fe(II) Co(II) Ni(II) Cu(II) Zn(II) Cd(II); Ln= L1-L6). Compounds were fully characterised by CHNS melting points FTIR UV-Vis mass spectroscopy magnetic susceptibility and NMR spectroscopy (1H 13C DEPT 1H-1H COSY 1H-13C HQMC). Physico-chemical characterisation confirmed a bidentate coordination mode of the CS2 moiety to the metal ion and complexes exhibit four coordinate structures in the solid state. However in solution the Ni(II) and Cu(II) complexes exhibit six coordinate structures.