Theoretical Studies on the Ethylene Purification Using Substituted Nickel Dithiolenes

Abstract

The world is running out of energy, thus energy preservation is of paramount importance. Using current technology, ethylene is purified from petroleum feed stocks using the very energy intensive cryogenic distillation method. However, a purification procedure based on the redox properties of nickel bis-dithiolene complexes has been theoretically studied, in order to design a more convenient route to ethylene purification. Several possible addition routes of ethylene to neutral and anionic Ni(S2C2(CN)2)2 complexes have been modeled using density functional theory. An intraligand addition and subsequent decomposition is preferred for the neutral complex, while the interligand adduct is formed in the presence of the anion, in line with previous experimental results. The effect of the anion, whose role is as a mediator in the initial step of the reaction, is discussed, and the ability of this compound to avoid poisoning by acetylene is investigated. The results from the CN substituted complex are then compared with that of ethylene addition to CF3, H, and OH substituted nickel dithiolene complexes.