The activation of alkane C-H bonds by oxidative addition and its reverse reaction, reductive elimination, are believed to occur via transient sigma-alkane complexes. This Account summarizes how isotope effects can be used probe the nature these intermediates points out some pitfalls in interpreting kinetic data. Comparisons made with arene other systems.

A well-defined iron complex (3) supported by a bis(phosphino)amine pincer ligand efficiently catalyzes both acceptorless dehydrogenation and hydrogenation of N-heterocycles. The products from these reactions are isolated in good yields. Complex 3, the active catalytic species reaction, is independently synthesized characterized, its structure confirmed X-ray crystallography. trans-dihydride intermediate (4) proposed to be involved existence verified NMR trapping experiments.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComparative reactivities of hydrocarbon carbon-hydrogen bonds with a transition-metal complexWilliam D. Jones and Frank J. FeherCite this: Acc. Chem. Res. 1989, 22, 3, 91–100Publication Date (Print):March 1, 1989Publication History Published online1 May 2002Published inissue 1 March 1989https://pubs.acs.org/doi/10.1021/ar00159a002https://doi.org/10.1021/ar00159a002research-articleACS PublicationsRequest reuse permissionsArticle...

Bi-, tri-, and tetracyclic isoquinoline salts were readily synthesized in excellent yields at room temperature from available starting materials after three reaction steps. Aromatic C−H activation was first promoted by sodium acetate with [Cp*MCl2]2 (M = Rh, Ir) to form cyclometalated compounds. Dimethylacetylenedicarboxylate then found insert into the metal−carbon bonds of Finally, insertion compounds underwent oxidative coupling desired regenerate [Cp*MCl2]2. All intermediate following...

Acceptorless dehydrogenation of alcohols, an important organic transformation, was accomplished with well-defined and inexpensive iron-based catalysts supported by a cooperating PNP pincer ligand. Benzylic aliphatic secondary alcohols were dehydrogenated to the corresponding ketones in good isolated yields upon release dihydrogen. Primary esters lactones, respectively. Mixed primary/secondary diols oxidized at alcohol moiety chemoselectivity. The mechanism reaction investigated using both...

Sodium acetate promoted C−H activation in a series of para-substituted phenyl imines has been examined using [Cp*MCl2]2 (M = Ir, Rh). The regioselectivity was investigated meta-substituted (−OMe, −CH3, −F, −COOMe, −CF3, and −CN) 2-phenylpyridines −CF3). It found that substrates with electron-donating substituents react significantly faster than electron-withdrawing substituents, which is consistent an electrophilic mechanism. also the extremely sensitive to steric effects, meta methyl group...

Benchmarking is a community-based and (preferably) community-driven activity involving consensus-based decisions on how to make reproducible, fair, relevant assessments. In catalysis science, important catalyst performance metrics include activity, selectivity, the deactivation profile, which enable comparisons between new standard catalysts. also requires careful documentation, archiving, sharing of methods measurements, ensure that full value research data can be realized. Beyond these...

Acceptorless, reversible dehydrogenation and hydrogenation reactions involving N-heterocycles are reported with a well-defined cobalt complex supported by an aminobis(phosphine) [PN(H)P] pincer ligand. Several N-heterocycle substrates have been evaluated under conditions. The cobalt-catalyzed amine step, key step in the process, has independently verified. Control studies related cycloalkanes suggest that direct acceptorless alkane pathway is unlikely. metal–ligand cooperativity probed...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe mechanism and thermodynamics of alkane arene carbon-hydrogen bond activation in (C5Me5)Rh(PMe3)(R)HWilliam D. Jones Frank J. FeherCite this: Am. Chem. Soc. 1984, 106, 6, 1650–1663Publication Date (Print):March 1, 1984Publication History Published online1 May 2002Published inissue 1 March 1984https://doi.org/10.1021/ja00318a018Request reuse permissionsArticle Views1508Altmetric-Citations284LEARN ABOUT THESE METRICSArticle Views are the...

The nickel(0) fragment [(dippe)Ni] has been found to react with a variety of aromatic nitriles. Initial pi-coordination the C=C and Ctbd1;N bonds 2-cyanoquinoline is lead ultimately C-CN oxidative addition. 3-Cyanoquinoline reacts similarly, although no eta(2)-CN complex observed. 2-, 3-, And 4-cyanopyridines initially give eta(2)-nitrile complexes that then quantitative formation addition products. Benzonitrile similarly but undergoes reversible insertion into Ph-CN bond an equilibrium...

The activation of several types carbon–fluorine bonds in alkanes, arenes and olefins, using the early transition metal complex Cp*2ZrH2, are described. Fluoroalkanes reduced to alkanes. Alkyl even aryl adducts containing β-fluorines undergo β-fluorine elimination. Evidence is presented that α-fluorine elimination also possible, occurs Cp*2Zr(CF3)H. studies include mechanistic investigations, which show evidence for a variety pathways depending on specific substrate.

Reaction of [(dippe)Ni(μ-H)]2 with allyl cyanide at low temperature quantitatively generates the η2-olefin complex (dippe)Ni(CH2CHCH2CN) (1). At ambient or above, olefin is converted to a mixture C−CN cleavage product (dippe)Ni(η3-allyl)(CN) (3) and olefin-isomerization products (dippe)Ni(η2-crotonitrile) (cis- trans-2), which form via C−H activation. The latter are exclusive longer reaction times, indicating that reversible crotononitrile complexes 2 more thermodynamically stable than...

A highly selective (>99%) tandem catalytic system for the conversion of ethanol (up to 37%) n-butanol, through Guerbet process, has been developed using a bifunctional iridium catalyst coupled with bulky nickel or copper hydroxides. These sterically crowded and hydroxides catalyze key aldol coupling reaction acetaldehyde exclusively yield C4 product, crotonaldehyde. Iridium-mediated dehydrogenation led development an ethanol-to-butanol process operated at lower temperature.

Replacement of precious metal catalysts in the Guerbet upgrade ethanol to n-butanol with first-row complex is highly appreciated due their economic and environmental friendliness. The manganese pincer complexes type [(RPNP)MnBr(CO)2] (R = iPr, Cy, tBu, Ph or Ad) are found be excellent for upgrading n-butanol. Under suitable reaction conditions an appropriate base, about 34% yield can obtained high selectivity. A detailed account on effect temperature, solvent, nature, proportion base used...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of arene carbon-hydrogen bond activation by (C5Me5)Rh(PMe3)(H)Ph. Evidence for precoordinationWilliam D. Jones and Frank J. FeherCite this: Am. Chem. Soc. 1982, 104, 15, 4240–4242Publication Date (Print):July 1, 1982Publication History Published online1 May 2002Published inissue 1 July 1982https://doi.org/10.1021/ja00379a031RIGHTS & PERMISSIONSArticle Views638Altmetric-Citations144LEARN ABOUT THESE METRICSArticle Views are the...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAlkane carbon-hydrogen bond activation by homogeneous rhodium(I) compoundsWilliam D. Jones and Frank J. FeherCite this: Organometallics 1983, 2, 4, 562–563Publication Date (Print):April 1, 1983Publication History Published online1 May 2002Published inissue 1 April 1983https://pubs.acs.org/doi/10.1021/om00076a020https://doi.org/10.1021/om00076a020research-articleACS PublicationsRequest reuse permissionsArticle Views864Altmetric-Citations138LEARN...

Significance Catalytic hydrogenation and dehydrogenation reactions are extremely important in organic chemistry recently for energy storage the form of chemical bonds. Although catalysts known which catalyze both reactions, rates conditions required two frequently very different due to differences associated with bonds be activated (C–H/O–H/N–H C = O/C N/H–H). The use a bifunctional catalyst would substantially simplify design processes related storage. In this work, organometallic complexes...

Hydrogenation of alkenes containing polarized C═C double bonds has been achieved with iron-based homogeneous catalysts bearing a bis(phosphino)amine pincer ligand. Under standard catalytic conditions (5 mol % (PNHPiPr)Fe(H)2(CO) (PNHPiPr = NH(CH2CH2PiPr2)2), 23 °C, 1 atm H2), styrene derivatives electron-withdrawing para substituents reacted much more quickly than both the parent and substituted styrenes an electron-donating group. Selective hydrogenation occurs in presence other reducible...

Here, we report an additive-free catalytic system for hydrogenation of carboxylic acid esters to alcohols with a well-defined cobalt pincer catalyst precursor. Various substrates, including methyl, ethyl, and benzyl esters, have been evaluated under conditions; however, methyl low reactivity compared those the corresponding ethyl esters. The biomass-derived γ-valerolactone successfully formed 1,4-pentanediol turnover number 3890 this system. Metal–ligand cooperativity is probed related...

A single homogeneous nickel(II) complex, supported by the tris(3,5-dimethylpyrazolyl)borate ligand and 2-hydroxyquinoline ancillary ligand, is shown to catalyze both acceptorless dehydrogenation of alcohols hydrogenation carbonyl compounds under mild conditions. Products from catalytic reactions were isolated with good yields. mechanistic investigation highlights critical role in catalysis argues against a stepwise pathway.

The complexes Pt(PEt3)3 and Pd(PEt3)3 cleave the C−C bond of biphenylene to give (PEt3)2Pt(2,2'-biphenyl), 1, (PEt3)2Pd(2,2'-biphenyl), respectively. Heating (PEt3)2Pt(2,2'-biphenyl) in presence leads cleavage a second (PEt3)2Pt(2,2'-tetraphenyl), 2, via Pt(IV) intermediate. 2 reductively eliminates tetraphenylene at 115 °C. At 120 °C reaction is catalytic; or 1 converts tetraphenylene. intermediates catalytic cycle have been identified, characterized by X-ray analysis. Under conditions...

The nickel hydride dimer [(dippe)NiH]2 (1) was found to react with a variety of organosulfur substrates under mild conditions leading C−S bond insertion adducts. transition-metal insertions into the bonds thiophene, benzothiophene, and dibenzothiophene are all reversible, lead new organometallic complexes when dissolved in hydrocarbon solvent. (dippe)Ni(η2-C,S-dibenzothiophene) (6) converts four species unique desulfurization reaction that is believed proceed via intermediacy late-metal...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTRoom-Temperature Desulfurization of Dibenzothiophene Mediated by [(i-Pr2PCH2)2NiH]2David A. Vicic and William D. JonesView Author Information Department Chemistry University Rochester Rochester, New York 14620 Cite this: J. Am. Chem. Soc. 1997, 119, 44, 10855–10856Publication Date (Web):November 5, 1997Publication History Received28 July 1997Published online5 November inissue 1...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTReversible Cleavage of Carbon−Carbon Bonds in Benzonitrile Using Nickel(0)Juventino J. Garcia and William D. JonesView Author Information Facultad de Química, Universidad Nacional Autonoma Mexico, D.F. 04510, Department Chemistry, University Rochester, New York 14627 Cite this: Organometallics 2000, 19, 26, 5544–5545Publication Date (Web):November 18, 2000Publication History Received3 October 2000Published online18 November inissue 1 December...