Zinc halides metal hydrides

A number of compounds having a direct zinc transition metal bond are known for long time, that is, zinc-bis(transition metal) such as Zn[Co(C04)]2 and transition metal zinc halides such as (CO)4Fe(ZnCl)2. However, organozinc-transition metal compounds RZn-TM are comparatively more recent. They can be prepared by hydrocarbon elimination between a diorganozinc derivative and a transition metal hydride (see Hydrides) (equation 35), but dialkyl- and diarylzinc compounds usually fail to react or react very slowly. Furthermore, when they do react they give unstable products that show a very strong tendency to disproportionate and cannot be isolated (equation 36). 

For chalcogenide thin films it is possible to use elemental S, Se, Te as precursors provided that the other source is a volatile and reactive metal. ZnS deposition using elemental zinc and sulphur was the first ALD process developed [4]. Therefore for precursors other than metals, the reactivity of elemental chalcogens is not sufficient. For other precursor types, including halides, 6-diketonates and organometalHcs, simple hydrides, such as H2S, H2Se and H2Te, have typically been used as a second precursor. 

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