Mechanistic Insights on the Hydrodesulfurization of Biphenyl-2-thiol with Nickel Compounds

Abstract

The reactivity of the nickel(I) dimer [(dippe)Ni(mu-H)](2) (1) with biphenyl-2-thiol was explored with the aim of clarifying the key step of sulfur extrusion during the hydrodesulfurization process using dibenzothiophene (DBT). These reactions were monitored by variable temperature NMR experiments which allowed the complete characterization and isolation of [(dippe)(2)Ni(2)(mu-H)(mu-S-2-biphenyl)] (3). The latter compound evolves to the terminal nickel-hydride [(dippe)Ni (eta(1)-C-2-biphenyl)(H)] (4) and transient [(dippe)NiS] (5), to ultimately yield [(dippe)(2)Ni(2)(mu-S)] (2) and biphenyl as the resulting HDS products. The reactivity of 1 and biphenyl-2-thiol was examined using different ratios of reactants, which allowed preparation of [(dippe)Ni(eta(1)-S-biphenyl-2-thiolate)(2)] (6) when using an excess of this substrate. The reactivity of 6 with 1 was addressed, yielding compound 2 and an equivalent amount of biphenyl.

Resolving Conformation Dichotomy for Y‐ and T‐Shaped Three‐Coordinate NiI Carbonyl Complexes with Relativistic DFT Analysis of EPR Fingerprints

“…[1,2] For instance, nickelexchanged zeolites play an important role in studying the mechanistic aspects of selective catalytic reduction of NO x [2] or selective hydrogenation of nitro aromatic compounds. [3] Phosphanylphenolate nickel complexes are active in olefin polymerization, [4] whereas the methanogenesis cycle is catalyzed by methylcoenzyme M (methyl-CoM) reductase with the cofactor F 430 comprising Ni I hydrocorphinoid.…”

ChemInform Abstract: Recent Developments in Palladium‐Based Bimetallic Catalysts

“…[138] The recent trend of environmental regulationi sb ecoming increasingly stringent with regard to sulfur content in fuels. [139][140][141][142][143][144] The conventional NiÀMo sulfide catalyst requiresahigh temperature for activation and it also deactivates rapidly owing to problemso fp articles intering and carbon deposition. [145,146] Thus, it is difficult for the conventional catalysts to manageadeep HDS.…”

Bond Activation with Low‐Valent Nickel in Homogeneous Systems

“…The latter is explained on the basis of the large steric hindrance that the substrate, the Grignard reagent and the ancillary ligand oppose to each other. [54] Closely related to the previous systems, the desulfurization reaction of the DBT-sulfones using low-valent nickel is currently being undertaken by our group, the oxidation of DBTs to their respective sulfones being a method employed by the industry to facilitate their separation from the main petroleum feedstock. For all the desulfurization experiments performed, the formation of MgS yields the driving force of reaction.…”