molybdenum dithiocarbamate (MoDTC) is a widely used automotive lubricant additive which is capable of producing tribologically suitable tribofilms under various operating conditions. It is an ideal lubricant because it has high shear and flow resistance, which is essential for efficient friction reduction. In addition, MoDTC is a green tribochemical catalyst that exhibits high stability and selectivity under mild and eco-friendly conditions.

Synthesis, reactivity and structure of dialkyldithiocarbamate stabilized molybdenum imido complexes

In the present thesis, we report the synthesis, reactivity and structure of a series of bis(arylimido) molybdenum dithiocarbamate complexes prepared by two methods. These include the thermolysis of [Mo(O)2] with an organic isocyanate and the treatment of [Mo(NR)2Cl2] with NH4[S2CNEt2].

The disulfur complexes, which are only formed from very bulky isocyanates, consist of a double sulphur-carbon bond cleavage of an additionally coordinated dithiocarbamate ligand. The molybdenum atom is coordinated by two phosphane-P atoms and the L2 di-anion by an additional phosphane-S bond, which is positioned around the gold atom ring, as shown in Figure 1.

Synthesis and properties of tribofilms generated from ZnDDP and MoDTC

Tribochemical spectra are compared between neat zinc dimethiophosphate (ZnDDP) and both zinc dimethiophosphate/MoDTC (ZDDP/MoDTC), which were synthesised by adding different concentrations of the respective compounds. The ZnS content of the tribofilms generated from both compounds was found to be very similar on the steel surface. The ZnDDP/MoDTC compounds were also shown to have a relatively high shear resistance and a very low coefficient of sliding friction.