Coordination behavior of three geometric isomers of indole-based S-benzyldithiocarbazone ligands towards nickel, zinc and cadmium divalent ions

► Indolecarbaldehyde S-benzyldithiocarbazones can show different coordination behavior. ► The 2- and 3-imineindole act as NS bidentate chelates, forming five-membered rings. ► The 7-imineindole can act as a NS bidentate chelate to form four-membered rings. ► With added base, the 7-imineidole acts as a NNS tridentate ligand.