Synthesis and Physical Investigation of Tellurium Dithiocarbamates

Abstract

A range of tellurium dithiocarbamates [Te(S2CNR2)2 and Te(S2CNR2)4 J were synthesised and used to study their ligand exchange reactions. The photo-reaction of solutions of these compounds with dioxygen was investigated. The tetrakis(dialkyldithiocarbamato) tellurium(IV) [Te(dtc)4] was found to be a good stabilizer for polypropylene (PP) during photo-oxidation. In addition, [Te(dtc)4] were superior stabilizers during thermal-oxidation in comparison to the metal dithiocarbamates such as zinc and nickel dithiocarbamates. It was also found that by changing the alkyl group of the dialkyldithiocarbamate, it is possible to obtain still better stabilizing activity. The preparation of (2-phenylazophenyl-C,N')tellurium(IV) trichloride (AzoTeCl3) is reinvestigated. Its crystal and molecular structure was determined. The structure of the compound is monomeric. The direct reaction of azobenzene and tellurium tetrachlorides gives AzoTeCl3, the 13C NMR of which is discussed. Finally, its reaction with hydrazine hydrate is reinvestigated and it was found that an excess of hydrazine gives the new ditelluride; bis(2-phenylazophenyl-C,N')ditelluride. Some new organotellurium dithiocarbamates [ArTe(dtc) and arTe(dtc)3, where Ar=2-phenylazophenyl- group and dtc=R2NCS2 were prepared. The crystal and molecular structure of dimethyl dithiocarbamato(2-phenylazophenyl-C,N')tellurium(II) was determined. The structure consists of monomeric molecules. Their I.R. and mass spectra have been studied. Also, ArTe(dtc)3 was used as a stabilizer for PP. These compounds appear to be good stabilizers during photo-oxidation but they show very low efficiency during thermal-oxidation. The crystal and molecular structure of acetato(2-phenylazophenyl-C,N')tellurium(II) and (2-phenylazophenyl-C,N')thiocyanatotellurium(II) were determined. The structure of the former consists of discrete molecules in which weak intramolecular Te...O interactions occur. However, the structure of the latter compound shows a very weak intermolecular Te...N interaction, which links the molecules in the form of dimers. Their preparation and I.R. spectra are discussed.