Repercussion of a 1,3-hydrogen shift in a hydride-osmium-allenylidene complex

Autor: Enrique Oñate, Andrea Vélez, Sonia Paz, Miguel A. Esteruelas
Přispěvatelé: Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), European Commission, Gobierno de Aragón, Ministerio de Economía y Competitividad (España)
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
instname
Digital.CSIC: Repositorio Institucional del CSIC
Consejo Superior de Investigaciones Científicas (CSIC)
Popis: An unusual 1,3-hydrogen shift from the metal center to the Cβ atom of the C3-chain of the allenylidene ligand in a hydride-osmium(II)-allenylidene complex is the beginning of several interesting transformations in the cumulene. The hydride-osmium(II)-allenylidene complex was prepared in two steps, starting from the tetrahydride dimer [(Os(H···H){κ3-P,O,P-[xant(PiPr2)2]})2(μ-Cl)2][BF4]2 (1). Complex 1 reacts with 1,1-diphenyl-2-propyn-1-ol to give the hydride-osmium(II)-alkenylcarbyne [OsHCl(≡CCH═CPh2){κ3-P,O,P-[xant(PiPr2)2]}]BF4 (2), which yields OsHCl(═C═C═CPh2){κ3-P,O,P-[xant(PiPr2)2]} (3) by selective abstraction of the Cβ–H hydrogen atom of the alkenylcarbyne ligand with KtBuO. Complex 3 is metastable. According to results of DFT calculations, the migration of the hydride ligand to the Cβ atom of the cumulene has an activation energy too high to occur in a concerted manner. However, the migration can be catalyzed by water, alcohols, and aldehydes. The resulting alkenylcarbyne-osmium(0) intermediate is unstable and evolves into a 7:3 mixture of the hydride-osmium(II)-indenylidene OsHCl(═CIndPh){κ3-P,O,P-[xant(PiPr2)2]} (4) and the osmanaphthalene OsCl(C9H6Ph){κ3-P,O,P-[xant(PiPr2)2]} (5). Protonation of 4 with HBF4 leads to the elongated dihydrogen complex [OsCl(η2-H2)(═CIndPh){κ3-P,O,P-[xant(PiPr2)2]}]BF4 (6), while the protonation of 5 regenerates 2. In contrast to 4, complex 6 evolves to a half-sandwich indenyl derivative, [Os(η5-IndPh)H{κ3-P,O,P-[xant(PiPr2)2]}][BF4]Cl (7). Phenylacetylene also provokes the 1,3-hydrogen shift in 3. However, it does not participate in the migration. In contrast to water, alcohols, and aldehydes, it stabilizes the resulting alkenylcarbyne to afford [Os(≡CCH═CPh2)(η2-HC≡CPh){κ3-P,O,P-[xant(PiPr2)2]}]Cl (8).
Financial support from the MINECO of Spain (Projects CTQ2017-82935-P and RED2018-102387-T (AEI/FEDER, UE)), Gobierno de Aragón (Group E06_20R and project LMP148_18), FEDER, and the European Social Fund is acknowledged.
Databáze: OpenAIRE
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