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

Abstract

Gas-phase reactions between R₂Zn (R=Me and Et) and ^tBuSH produce cluster complexes of the type [RZnS^tBu]_n. These clusters, along with [MeZnS^tBu(py)]₂ (py=pyridine), have been characterised by ¹³C{¹H} solid-state NMR. On heating to 100°C in the solid-state, the complexes [MeZnS^tBu]₅ and [MeZnS^tBu(py)]₂ release dimethylzinc (Me₂Zn) to form the zinc bis(thiolate) compound, [Zn(S^tBu)₂]_n, with further heating (>200°C) leading to the formation of ZnS. The ethyl analogue, [EtZnS^tBu]₅, does not lose Et₂Zn on heating and thermogravimetric analysis (TGA) suggests a different decomposition pathway, one which mainly involves loss of the 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, [MeZnS^tBu]₅ and [EtZnS^tBu]₅, and the dimer, [MeZnS^tBu(py)]₂, proceeds at higher temperature (200-350°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 [RME^tBu]_n are also produced from the gas-phase reactions of Me₂Zn with ^tBuSeH and from Me₂Cd with ^tBuSH.

References

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