PREPARATION OF NEW SELENIUM-RICH SELENIDES, CRSE3, MOSE-APPROXIMATE-TO-5, WSE-APPROXIMATE-TO-6-7, AND RESE-APPROXIMATE-TO-6-7 AND KNOWN SELENIDES, BY THE REACTION OF METAL-CARBONYLS WITH SELENIUM

The reaction of the transition-metal carbonyls, Cr(CO)6, Mn2(CO)10, Fe(CO)5, Co2(CO)8, Mo(CO)6, W(CO)6 and Re2(CO)10, with selenium in 1,2-dichlorobenzene heated under reflux produced a number of known transition-metal selenides, MnSe, MnSe2, FeSe2, CoSe2, MoSe2 and WSe2 and four new selenium-rich compounds, CrSe3, MoSe(almost-equal-to 5), WSe(almost-equal-to 6-7), and ReSe(almost-equal-to 6-7). The new selenides, with high selenium-to-metal ratios, were obtained as amorphous solids, while the known compounds, MnSe, MnSe2, FeSe2, CoSe2 were formed as polycrystalline powders and MoSe2 and WSe2 as poorly ordered fibres. The products were characterised by analytical electron microscopy and powder X-ray diffraction and MoSe(almost-equal-to 5) was further characterised using thermal methods.