Continuous Shape Measure of electronic effect free steric distortions in tris(dithiocarbamato)indium(III): Synthesis, spectral, electrochemical, single crystal X-ray structural investigations and BVS calculations on tris(dithiocarbamato)indium(III) complexes

Geometrical distortions from an ideal octahedral geometry (iOh) towards an ideal trigonal prism (itp) in tris(dithiocarbamato)indium(III) complexes have been quantified by Continuous Shape Measure (CShM) analysis. Three tris(disubstituted dithiocarbamato)indium(III) complexes, cyclohexylmethyldithiocarbamate (chmdtc) (1), cyclohexylethyldithiocarbamate (chedtc) (2) and dicyclohexyldithiocarbamate (dchdtc) (3), have been prepared and characterized by spectral, cyclic voltammetric and single crystal X-ray structural techniques. The electronic effects are at a minimum for trivalent indium and the distortions follow the order: (3) > (1) > (2), as per the CShM values. The IR spectra indicate a contribution of the thioureide form of the dithiocarbamates to the stabilization of the compounds, with a characteristic C-N stretch in the range 1446-1475 cm(-1). H-1 NMR spectra indicate that the protons in the vicinity of the thioureide nitrogen are the most affected on complexation. C-13 NMR spectra showed the characteristic thioureide carbon signals at 201.18, 200.98 and 200.94 ppm for complexes (1), (2) and (3) respectively. Cyclic voltammetric investigations revealed three single electron additions to the trivalent indium. The single crystal X-ray structures showed little change in the In-S and thioureide C-N bond distances or the S-In-S bite angles with changes in the steric demands, in the absence of any significant electronic effects. Bond Valence Sums (BVS) of the complexes identified the formal oxidation of indium to be +3 and the observed deviations show the increased covalent bonding. Nano indium sulfides have been prepared from the dithiocarbamates through a non-conventional solvothermal process. The nanosulfides have been characterized by SEM and EDX techniques. The ease and yield of formation follow the order: (3) > (1) > (2).