Lubricating compositions containing bispiperazido phosphorus and trispiperazido phosphorus compounds

A lubricating composition which comprises a major amount of a lubricating oil and 0.1%-10% by weight of a piperazidophosphorus compound of the formula:

• ##STR30## and lubricating-oil-compatible salts of such compounds, wherein X represents an oxygen or sulphur atom or is absent,
• Y represents (i) an aliphatic, cycloaliphatic, or aromatic hydrocarbon group or an N-containing heterocyclic group;
• (ii) a group of the formula -NR.sub.2 in which each group R represents a hydrogen atom, an aliphatic, cycloaliphatic, or aromatic hydrocarbon group or an N-containing heterocyclic group, or the two groups R, together with the nitrogen atom to which they are attached, represent a N-containing heterocyclic ring;
• (iii) a group of the formula --OR in which R has the meaning given above;
• or (iv) a group of the formula:
• ##STR31## R.sup.1 represents an inert substituent on the piperazine ring;
• R.sup.2 represents a hydrogen atom, an aliphatic, cycloaliphatic or heterocyclic radical, an acyl group, a sulphonyl group, a phosphorus-containing group PKR.sub.2.sup.3 or a carbamoyl group, CONHR;
• R.sup.3 represents an aliphatic, cycloaliphatic, or aromatic hydrocarbon group or a group of the formula --OR, --SR, or --NR.sub.2 ;
• and
• n represents O or an integer, and salts of such compounds in which at least one of the groups R.sup.2 represents a hydrogen atom;
• but with the proviso that Y does not represent dimethylamino when X represents oxygen and R.sup.1 and R.sup.2 both represent hydrogen.