Structural properties of Co(Ⅲ), Hg(Ⅱ) and Pb(Ⅱ) N-ethyl-N-phenyl-dithiocarbamates and their application in the rubber industry

摘要

The present paper is devoted to the study of structural properties of Co(epdtc)_3, Hg(epdtc)_2 and Pb(epdtc)_2 (epdtc = N-ethyl-N-phenyldithiocarbamate) by X-ray structural analysis and their influence on the kinetics of cure of rubber compounds, by means of differential scanning calorimetry (DSC). N-ethyl-N-phenyldithiocarbamates belong to a group of chelating ligands. The dark green complex Co(epdtc)_3 exhibits an octahedral coordination of the central Co atom. The pale yellow dimeric complex Hg(epdtc)_2 exhibited distorted tetragonal pyramidal coordination. The pale yellow complex Pb(epdtc)_2 with two independent molecules in the unit cell, exhibited distorted tetragonal pyramidal coordination with the lead atom in the top of the pyramid. The values of chelate angle S-M-S decrease with the increase of ionic radii of central atoms by this order: Co(epdtc)_3 > Hg(epdtc)_2 > Pb(epdtc)_2. Kinetic study of the cure process shows that studied compounds decrease the reaction order and the values of rate constants increase by this order: Hg(epdtc)_2 < Pb(epdtc)_2 < Co(epdtc)_3.