First example of molybdenum atoms in the network of high temperature Chevrel phases: Mo-y[Mo6Se8-xSx]

In the literature Mo6Se8-xSx (0 less than or equal to x less than or equal to 4) Chevrel phase binaries are stable compounds, synthesized by solid sta te reaction from stoichiometric mixture of MoS2, MoSe2, and Mo powders at 1 200 degrees C. We report the single-crystal structure of these compounds, T he structural determinations show as expected a classical Chevrel phase str ucture with a framework of pseudomolecular Mo6Se8-xSx cubic units but furth ermore exhibit molybdenum atoms in the channels of the host structure of th ese compounds, leading to the new formula Mo-y[Mo6Se8-xSx] with 0 less than or equal to x less than or equal to 5 and y similar to 0.3. These extra mo lybdenum atoms stabilize the Chevrel phase host network and seem to be link ing with a molybdenum atom of the Mo, cluster, forming a kind of Mo, cluste r. (C) 1999 Academic Press.