Computational studies on the effects of substituents on the structure and property of zinc dialkyldithiophosphates

Abstract

The substituent effect on the structure and property of zinc dialkyldithiophosphates (ZDDPs) have been investigated by DFT calculations. More than ten kinds of substituents including alkyl and aryl groups were chosen for assembling more than twenty ZDDPs. The structural features, thermal decomposition of ZDDP and the hydrolysis of alkaline tetranuclear zinc molecules with various alkyl and aryl substituents have been examined. It is found that the substituents have almost no effect on their central structures, but have significant effect on the thermal decomposition of alkyl- and aryl-substituted ZDDPs and their dimers. The calculations on the hydrolysis of tetranuclear ZDDPs suggest that the reaction free energies are affected by the substituents and the hydrolysis temperature. The radical species derived from ZDDP decomposition tends to be adsorbed on metal surface via multi-coordination manner.