Bisoxazoline-pincer ligated cobalt-catalyzed hydrogenation of alkenes

Ritz, Mikhaila D.; Parsons, Astrid M.; Palermo, Philip N.; Jones, William D.

doi:10.1016/j.poly.2020.114416

Cited by 3 publications

(2 citation statements)

References 26 publications

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“…In the area of cobalt chemistry, reports from several groups have described the catalytic hydrogenation activity of well-defined cobalt catalysts featuring pincer ligands. − These catalysts have been applied successfully for the hydrogenation of olefins and semi-hydrogenation of alkynes, with several systems displaying impressive stereoselectivities. Despite this success, no unified mechanistic picture has arisen comparable to the better understood features of H 2 activation and olefin insertion at play with heavier Group 9 metals.…”

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confidence: 99%

Catalytic Hydrogenation of Alkenes and Alkynes by a Cobalt Pincer Complex: Evidence of Roles for Both Co(I) and Co(II)

2021

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The Co(I) complex, [Co(N 2 )( Cy PNP)] ( Cy PNP = anion of 2,5-bis-(dicyclohexylphosphinomethyl)pyrrole), is active toward the catalytic hydrogenation of terminal alkenes and the semi-hydrogenation of internal alkynes under 2 bar of H 2 (g) at room temperature. The products of alkyne semi-hydrogenation are a mixture of E-and Z-alkenes. By contrast, use of the related cobalt(I) precatalyst, [Co(PMe 3 )-( Cy PNP)], results in formation of exclusively Z-alkenes. A semi-stable Co(II) species, [CoH( Cy PNP)], can also be generated by treatment of degassed solutions of [Co(N 2 )( Cy PNP)] with H 2 . The Co II -hydride displays activity toward both alkene hydrogenation and isomerization, but its instability hampers implementation as a catalyst. Several species relevant to potential catalytic intermediates have been isolated and detected in solution. These compounds include alkene and alkyne adducts of Co(I) as well as a Co(III) dihydride species. Catalytic results with the compounds examined are most consistent with a process involving shuttling between Co(I) and Co(III) states. However, generation of small quantities of Co(II) during catalytic turnover appears to be responsible for the isomerization observed for alkyne semi-hydrogenation. The interplay of cobalt oxidation states within the same catalyst system is discussed in the context of mechanistic scenarios for catalytic hydrogenation.

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Section: Introductionmentioning

confidence: 99%

Catalytic Hydrogenation of Alkenes and Alkynes by a Cobalt Pincer Complex: Evidence of Roles for Both Co(I) and Co(II)

2021

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“…Complexes that feature cobalt(I) or cobalt(II) centers supported by pincer ligands have emerged as an important class of olefin hydrogenation catalysts in their own right (Chart ). , In particular, work by Chirik, ,− Hanson, Lu, , Jones, Fout, Gade, Tonzetich, Anderson, Huang, and Peters , has demonstrated the utility of pincer-ligated cobalt complexes to efficiently catalyze olefin hydrogenation at room temperature with low catalyst loading.…”

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confidence: 99%

Catalytic Hydrogenation of Terminal Alkenes by a (PPP) Pincer-Ligated Cobalt(II) Complex

et al. 2023

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A Co(II) complex, (PP H P)CoI 2 , was synthesized and evaluated as a precatalyst for the hydrogenation of terminal alkenes under mild conditions (1 atm H 2 , ambient temperature) using KBEt 3 H as an activator. This catalytic system was found to be active for terminal alkene substrates, including 1,1′-disubstituted alkenes, and to exhibit modest air and moisture stability. A preliminary investigation into substrate scope and functional group tolerance was performed. Upon the completion of catalytic reactions, the sole metal complex observed was identified as the dimeric species [(PPP)CoH] 2 suggesting that the catalytically active species may be a cobalt hydride monomer.

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Catalytic and mechanistic studies of a highly active and E-selective Co(ii) PNN^H pincer catalyst system for transfer-semihydrogenation of internal alkynes

Decker

Wei

Rabeah

et al. 2022

Inorg. Chem. Front.

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Bisoxazoline-pincer ligated cobalt-catalyzed hydrogenation of alkenes

Cited by 3 publications

References 26 publications

Catalytic Hydrogenation of Alkenes and Alkynes by a Cobalt Pincer Complex: Evidence of Roles for Both Co(I) and Co(II)

Catalytic Hydrogenation of Alkenes and Alkynes by a Cobalt Pincer Complex: Evidence of Roles for Both Co(I) and Co(II)

Catalytic Hydrogenation of Terminal Alkenes by a (PPP) Pincer-Ligated Cobalt(II) Complex

Catalytic and mechanistic studies of a highly active and E-selective Co(ii) PNN^H pincer catalyst system for transfer-semihydrogenation of internal alkynes

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Bisoxazoline-pincer ligated cobalt-catalyzed hydrogenation of alkenes

Cited by 3 publications

References 26 publications

Catalytic Hydrogenation of Alkenes and Alkynes by a Cobalt Pincer Complex: Evidence of Roles for Both Co(I) and Co(II)

Catalytic Hydrogenation of Alkenes and Alkynes by a Cobalt Pincer Complex: Evidence of Roles for Both Co(I) and Co(II)

Catalytic Hydrogenation of Terminal Alkenes by a (PPP) Pincer-Ligated Cobalt(II) Complex

Catalytic and mechanistic studies of a highly active and E-selective Co(ii) PNNH pincer catalyst system for transfer-semihydrogenation of internal alkynes

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Catalytic and mechanistic studies of a highly active and E-selective Co(ii) PNN^H pincer catalyst system for transfer-semihydrogenation of internal alkynes