Chalcogen-bridged copper clusters

Scheme 3.2 General synthesis route for the formation of phosphine-ligated, chalcogen-bridged copper clusters.

The copper atoms in the vast majority of the clusters can be assigned a formal charge of +1, while the chalcogen ligands are formally viewed as E or RE groups. Some of the selenium-bridged species, however - and nearly all copper telluride clusters - form nonstoichiometric compounds that display mixed valence metal centers in the formal oxidation states 0 and +I or +I and +11. These observations correlate with those made for the binary phases CU2S, Cu2 xSe, and Cu2- Te [38-40]. 

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