The use of phosphine chalcogenides in the preparation of cobalt chalcogenides

Dicobalt octacarbonyl reacts with TePⁿBu₃, SePⁿBu₃ or SPⁿBu₃ to give solid state cobalt telluride, cobalt selenide and cobalt sulfide, respectively. In each case a cluster compound of the form Co₆E₈ (PⁿBu₃)₆ can be isolated from the reaction of the phosphine chalcogenide with cobalt carbonyl, and subsequently carried on to the solid state product. In this sense the Co₆E₈ clusters are intermediates in the molecules-to-solids processes. In the case of Se, another Co/Se cluster can be isolated: Co₄Se₂(CO)₆(PⁿBu₃ )₄. This complex also fits into the molecules-to-solids pathway inasmuch as it arises from Co₂(CO)₈ and SePⁿBu₃, and it is converted to the Co₆Se₈ cluster when treated with phosphine selenide. These results show that molecules-to-solids pathways originally uncovered in studying reactions of TePEt₃ can be extended to other trialkylphosphines and other chalcogens.