Abstract
The reactions of niobium pentaisopropoxide with the sulphur donor ligands derived by the condensation of S-benzyl dithiocarbazate with salicylaldehyde, o-hydroxy acetophenone, 2,4-pentanedione or 1-phenyl-1,3-butanedione have been investigated in 1:1, 1:2, 2:5 and 1:3 molar ratios in anhydrous benzene. These ligands act as dinegatively charged tridentate species, and coordinate to the central niobium(V) atom through the thiolo-sulphur by proton exchange the azomethine nitrogen and the hydroxo/keto oxygen. On the basis of vibrational, electronic and proton nuclear magnetic resonance spectroscopy, conductance, thermogravimetric and magnetic susceptibility measurements, probable structures have been assigned to these complexes.