Molybdenum compounds and lubricating compositions containing them

A lubricating composition consists essentially of a blend of a mineral or synthetic lubricating oil and a compound of the formula where R1 and R2, which may be the same or different, are alkyl, alkenyl, or alkynyl groups preferably having 1-20 carbon atoms, and the X's are oxygen or sulphur atoms, at least one of the X's being an oxygen atom. Preferably R1 and R2 are alkyl groups, especially branched chain alkyl groups, but where R1 and/or R2 are alkenyl or alkynyl groups, the group(s) may contain more than one multiple bond. The molybdenum compounds are suitably used in an amount of from 0.1 to 5% by weight of the lubricating composition. In the examples, lubricating compositions are prepared from an SAE90 refined mineral lubricating oil and one of dithiomolybdenyl acetylacetonate, dithiomolybdenyl stearoylacetonate, dithiomolybdenyl lauroyl - pivaloyl - methanate or dithiomolybdenyl oleoyl-pivaloyl-methanate.ALSO:The invention comprises compounds of the Formula I where R1 and R2, which may be the same or different, are alkyl, alkenyl or alkynyl groups preferably having 1-20 carbon atoms and the X's are oxygen or sulphur atoms, at least one of the X's being an oxygen atom. Preferably, R1 and R2 are alkyl groups, especially branched chain alkyl groups, but where R1 and/or R2 are alkenyl or alkynyl groups, the group(s) may contain more than one multiple bond. They may be prepared by reacting a compound of the Formula II wherein R1, R2 and X are as above, with sulphur in an inert atmosphere preferably in a solvent and at an elevated temperature which is preferably between 100 DEG and 200 DEG C. A suitable solvent is the diketone shown chelated in Formula I. An alternative method of preparation is to react molybdenum hexacarbonyl with sulphur and a diketone or monothiodiketone of the formula R1C(X)CH2C(X)R2, where R1, R2 and X are as previously stated. In this method the reaction mixture generates its own inert atmosphere of carbon monoxide. In the examples dithiomolybdenyl acetyl-acetonate is prepared by the reaction of molybdenum triacetylacetonate with sulphur in acetylacetone and solvent and also by the reaction of molybdenum hexacarbonyl with sulphur and acetylacetone, dithiomolybdenyl stearoylacetonate is prepared by reacting molybdenum hexacarbonyl with stearylacetone and sulphur, dithiomolybdenyl lauroyl-pivaloyl methanate is prepared by reacting molybdenum hexacarbonyl with lauroyl-pivalo