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

Gas-phase reactions between R2Zn (R = Me and Et) and (BuSH)-Bu-t produce cl uster 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 comp lexes [(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), wi th further heating (> 200 degrees C) leading to the formation of ZnS. The e thyl analogue, [(EtZnSBu)-Bu-t](5), does not lose Et2Zn on heating and ther mogravimetric analysis (TGA) suggests a different. decomposition pathway, o ne which mainly involves loss of he; organic moieties without the concurren t loss of volatile Zn or S compounds, although ZnS is again the final therm al decomposition product. The decomposition of the involatile pentamers, [( MeZnSBu)-Bu-t](5) and [(EtZnSBu)-Bu-t](5), and the dimer, [(MeZnSBu)-Bu-t(p y)](2), proceeds at higher temperature (200-350 degrees C) to give agglomer ates of ME nanoparticulate material, with the individual particles having d iameters of 2-20 nm in all cases. The mechanistic pathway by-which these cl usters decompose appears to be highly dependent upon the R group(Me or Et) present,within the cluster. Preliminary results suggest that complexes of t he 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.