Gas phase formation of zinc/cadmium chalcogenide cluster complexes and their solid state thermal decomposition to form II-VI nanoparticle materials

Gas-phase reactions between R2Zn (R = Me and Et) and (BuSH)-Bu-t produce cluster complexes of the type [(RZnSBu)-Bu-t](n). These clusters, along with [(MeZnSBu)-Bu-t(py)](2) (py = pyridine), have been characterfsedby C-13{H-1} solid-state NMR. On heating to 100 degrees C in the solid-state, the complexes [(MeZnSBu)-Bu-t](5) and [(MeZnSBu)-Bu-t(py)](2) release dimethylzinc (Me2Zn) to form the zinc bis(thiolate) compound, [Zn((SBu)-Bu-t)(2)](n), with further heating (> 200 degrees C) leading to the formation of ZnS. The ethyl analogue, [(EtZnSBu)-Bu-t](5), does not lose Et2Zn on heating and thermogravimetric analysis (TGA) suggests a different. decomposition pathway, one which mainly involves loss of he; organic moieties without the concurrent loss of volatile Zn or S compounds, although ZnS is again the final thermal decomposition product. The decomposition of the involatile pentamers, [(MeZnSBu)-Bu-t](5) and [(EtZnSBu)-Bu-t](5), and the dimer, [(MeZnSBu)-Bu-t(py)](2), proceeds at higher temperature (200-350 degrees C) to give agglomerates of ME nanoparticulate material, with the individual particles having diameters of 2-20 nm in all cases. The mechanistic pathway by-which these clusters decompose appears to be highly dependent upon the R group(Me or Et) present,within the cluster. Preliminary results suggest that complexes of the type [(RMEBu)-Bu-t](n) are also produced from the gas-phase reactions of Me2Zn with (BuSeH)-Bu-t and from Me2Cd with (BuSH)-Bu-t.