BREAKING C-S BONDS WITH TRANSITION-METAL COMPLEXES - A REVIEW OF MOLECULAR APPROACHES TO THE STUDY OF THE MECHANISMS OF THE HYDRODESULFURIZATION REACTION

In spite of the large scale industrial applications of the hydrodesulfurization (HDS) process, and of the considerable number of studies of this reaction on heterogeneous catalysts, the mechanisms involved are not yet clearly understood. In this article we first summarize the main mechanistic pathways that have been proposed to occur on surfaces for HDS of thiophenes, and then review those aspects of coordination and organometallic chemistry that are most pertinent to the activation, desulfurization and hydrogenation of thiophenes on metal complexes. The examples described constitute excellent molecular analogues of the species and reactions that are thought to intervene in heterogeneous catalysis, and thus complement surface studies and contribute to the understanding of this important reaction.