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.