Synthesis of polymer-supported triphenylphosphine oxide complexes of divalent copper and cobalt. A study on their reactivity with sulfur dioxide

Abstract

Polymer-supported triphenylphosphine oxide dihalide and dinitrate complexes of copper(II) and cobalt(II), ML n X 2· xH 2O (L = polystyryl diphenylphosphine oxide; n =2–4; x = 0–7; X = Cl −, Br − and NO 3 −) have been synthesised and characterised. Their reactions with sulfur dioxide have been investigated in the solid state and in toluene slurries at room temperature. The absorption of SO 2 by these complexes and the free polymeric ligand was also studied by thermogravimetrical analysis (TGA) in the 230-30°C temperature range. All the copper and some cobalt complexes form SO 2 adducts on exposure to sulfur dioxide in the solid state at room temperature. When the complexes were exposed to SO 2 as toluene slurries, the initial stoichiometry of some complexes was found to be modified by the loss of one or two equivalents of neutral polymeric ligand. TGA studies show that SO 2 adducts can only be formed from initial complexes. For all nitrate complexes studied, at room temperature (solid state or toluene slurries) and high temperature, it was found that nitrate ions were displaced and replaced by sulfate groups. These reactions have been found to be dependent on the medium of the reaction, on the temperature and on the nature of metal, anionic and neutral ligand. Some air scale stable SO 2 adducts of accurate formulae could be isolated and their infrared spectra have been recorded. Sulfur dioxide desorption of some SO 2 adducts has also been studied by heating at 160°C and reduced pressure for 1 h.