A Theoretical Investigation on the Dynamic Behavior of Molybdenum Dithiocarbamate Molecule in the Engine Oil Phase

Abstract

We investigated the decomposition reaction mechanism of a molybdenum dithiocarbamate (MoDTC) molecule using computational chemistry methods: density functional theory and hybrid quantum chemical/classical molecular dynamics methods. The density functional theory results showed that the linkage isomerization reaction of the MoDTC preferentially takes place than its direct decomposition reaction. During a hybrid quantum chemical/classical molecular dynamics simulation, the linkage isomer of MoDTC was observed and subsequently bond weakening of its Mo-O was also observed in the polyalphaolefine phase. From these results, we proposed a new decomposition reaction pathway of the MoDTC molecule: it first forms its linkage isomer as the intermediate in the engine oil phase then decomposes into molybdenum disulfide and monothiocarbamic acid molecules on the rubbing nascent surfaces.