Molybdenum Tetrachloride, MoCl₄

Molybdenum Tetrachloride, MoCl₄, may be prepared by the action of chlorine at a high temperature upon molybdenum, or upon the oxide or sulphide mixed with carbon; by heating the trichloride to redness in a stream of dry carbon dioxide, both the tetrachloride and the dichloride of molybdenum are obtained, although the former does not distil without decomposition.

Molybdenum tetrachloride forms a semi-crystalline deliquescent powder, unstable in air, in which, if heated, it yields the oxychloride MoO₂Cl₂ and dichlormolybdic acid MoO₃.2HCl; it is also stated to be converted spontaneously into the pentachloride and trichloride. If sufficiently heated - though below 1330° C. - it is reduced to the metal. In water, alcohol, ether, and in dilute sulphuric acid it gives unstable solutions.

The double salt 3MoCl₄.2NH₄Cl.6H₂O has been described.