Abstract IN WHICH M is selected from the transition metals and zinc, cadmium, tin, lead, antimony and bismuth; n is the oxidation degree of M, R1 and R2 are each a monovalent hydrocarbon radical having one to 20 carbon atoms and 0 to 3 heteroatoms selected from the group consisting of halogen, oxygen, sulfur and nitrogen; Y is selected from the hydrogen atom and the radicals R'', R''O, R''S and R''CO in which R'' is a hydrocarbon radical of one to 20 carbon atoms; Y and R1 or R2 may form a divalent hydrocarbon radical containing one to 20 carbon atoms and 0-3 heteroatoms selected from oxygen, sulfur and nitrogen; and each atom Z is oxygen or sulfur, at least one of the 2n atoms Z being sulfur. A lubricating composition comprising a lubricating oil and at least one thioorganometallic complex of the general formula :