4819-96-9Relevant academic research and scientific papers
Hydrodesulfurization of Organosulfur Heterocycles by Metal Hydride-Nickel(0) Complexes: Accelerated Single-Electron Transfer in Carbon-Sulfur Bond Cleavage
Eisch, John J.,Hallenbeck, Lawrence E.,Han, Kyoung Im
, p. 7763 - 7767 (1986)
The novel nickel complex, LiAlH2(THF)n.C10H8N2.Ni (2), which result from the interaction in a THF solution of (2,2'-bipyridyl)(1,5-cyclooctadiene)nickel (1) with LiAlH4 in a 1:1 molar ration is powerful desulfurizing agent in homogeneous solution for such aromatic sulfur heterocycles as dibenzothiophene (3), phenoxathiin (11), phenothiazine (12), and thianthrene(13).When employed in a 2:1 molar ratio with the heterocyclic substrate, 2 produces the corresponding ring-opened desulfurization products (biphenyl, diphenyl ether, diphenylamine, and benzene, respectively) in high yields.In contrast, 1 effects predominantly ring contraction during desulfurization and yields dibenzofuran, carbazole, and dibenzothiophene from 11, 12, and 13, respectively.From consideration of relative desulfurization rates for substituted dibenzothiophenes, deuterium labeling experiments, and the chemical reactivity differences for 1 and 2, it is concluded that these reagents desulfurize via single-electron-transfer mechanism and that radical anoins are crucial reactive intermediates.The greater reactivity of 2 is ascribed to its anionic nickel character.
Experimental and theoretical studies on gold(iii) carbonyl complexes: reductive C,H- And C,C bond formation
Ahrens, Alexander,Dreuw, Andreas,Hashmi, A. S. K.,Hoffmann, Marvin,Karger, Leonhard F. P.,Lustosa, Danilo M.,Rudolph, Matthias
supporting information, p. 8752 - 8760 (2021/07/02)
The reactivity of cationic (C^C)gold(iii) carbonyl complexes was investigated. While thein situ-formed IPrAu(bph)CO+complex (bph = biphenyl-2,2′-diyl) does not undergo a migratory insertion of CO into the neighboring gold-carbon bond, nucleophiles can attack the coordinated CO moiety intermolecularly. Water as a nucleophile initiates a CO2extrusion combined with a reductive C,H bond formation. The rapid formation of a gold(i) species from an intermediary gold(iii) carbonyl has not been observed before and shows a significant difference in reactivity between (C^C) and (C^N^C)gold(iii) carbonyls. The latter have been reported to form stable gold(iii) hydridesviathe WGS reaction. In the case of methanol acting as a nucleophile attacking the gold(iii) carbonyl, no extrusion of CO2is observed. Instead an intermediary gold(iii) carboxyl complex forms an aryl carboxylateviareductive C-C bond elimination. Experimental and theoretical studies on the mechanism explain the observed selectivities and give new insights into the reactivity of elusive gold(iii) carbonyls.
Desulfurization of Dibenzothiophene by Nickel(0) Complexes: Evidence for Electron Transfer in Oxidative Additions
Eisch, John J.,Hallenbeck, Lawrence E.,Han, Kyoung Im
, p. 2963 - 2968 (2007/10/02)
Two equivalents of the complex (2,2'-bipyridyl)(1,5-cyclooctadiene)nickel(0) cleave dibenzothiophene in homogeneous media to form nickel-substituted biphenyl derivatives and nickel sulfide.The cleavage proceeds more readily in THF than in benzene solution, and excess amine (either bipyridyl or pyridine) retards the reaction.Neither biphenylene nor 2-phenylbenzenethiol was detectable transient in the desulfurization process.The possible fleeting formation of biphenylene was ruled out by a study of the desulfurized products obtained from the 2,8-dimethyl and the 3,7-dimethyl derivatives of dibenzothiophene.A possible role of nickel hydride in some of the C-S bond cleavage is suspected from the observed effects of either acid or LiAlH4 used in the workup of the reaction mixture.The reaction is not catalytic in nickel when an excess of LiAlH4 is used; this indicates that Ni(0) cannot be regenerated from NiS under these conditions.The observed cleavage of ca. 50percent of the dibenzothiophene by 2 equiv of (C10H8N2)Ni(C8H12) is ascribed to the gradual formation of (C10H8N2)2Ni, which is ineffectual in cleaving dibenzothiophene.Finally, the relative reactivity of the dibenzothiophenes (dibenzothiophene > 2,8-dimethyldibenzothiophene >> 3,7-dimethyldibenzothiophene), the relative effectiveness of amine donors or solvents, and the observed hydrogen abstraction from the solvent are interpreted in terms of an electron-transfer mode of action by the nickel(0) desulfurizing agent.
