Osmium- And Iridium-Promoted C-H Bond Activation of 2, 2'-Bipyridines and Related Heterocycles: Kinetic and Thermodynamic Preferences

Cancela, L. (Universidad de Zaragoza) ; Esteruelas, M.A. ; López, A.M. (Universidad de Zaragoza) ; Oliván, M. ; Oñate, E. ; San-Torcuato, A. ; Vélez, A. (Universidad de Zaragoza)

Resumen: The d2-hexahydride complex OsH6(PiPr3)2 (1) promotes the activation of C-H bonds of 2, 2'-bipyridines and related heterocycles. The study of the same reactions with the deuteride counterpart OsD6(PiPr3)2 (1-d) reveals that the activation of the C-H bonds situated in the sterically less hindered positions is kinetically preferred. However, the isolated products are the result of the thermodynamic control of the reactions. Thus, reactions of 1 with 2, 2'-bipyridine, 6-phenyl-2, 2'-bipyridine, and 6-methyl-2, 2'-bipyridine give the "rollover cyclometalation" products OsH3{¿2-C, N-[C5(R)H2N-py]}(PiPr3)2 (R = H (2), Ph (3), Me (4)), whereas 3, 5-dimethyl-6-phenyl-2, 2'-bipyridine affords OsH2{¿3-C, N, C-[C5H3N-(Me)2py-C5H4]}(PiPr3)2 (5), containing a dianionic C, N, C-pincer ligand. The behavior of substrates pyridyl-benzimidazolium and -imidazolium is similar. Reaction of 1 with 3-methyl-1-(6-phenylpyridin-2-yl)-1H-benzimidazolium tetrafluoroborate leads to OsH3{¿2-C, C-[MeBzim-C5(Ph)H2N]}(PiPr3)2 (6), bearing an anionic Cpy, CNHC-chelate. On the other hand, 3-methyl-1-(6-phenylpyridin-2-yl)-1H-imidazolium tetrafluoroborate yields [OsH2{¿3-C, N, C-(MeIm-py-C6H4)}(PiPr3)2]BF4 (7), containing a monoanionic C, N, C-pincer with a NHC-unit coordinated in an abnormal fashion. The reactivity pattern of these substrates is also observed with the d4-iridium-pentahydride IrH5(PiPr3)2 (8), which has generated IrH2{¿2-C, N-[C5(R)H2N-py]}(PiPr3)2 (R = H, (9), Ph (10)) and IrH{¿3-C, N, C-[C5H3N-(Me2)py-C5H4]}(PiPr3)2 (11). The osmium(IV)-carbon bonds display a higher degree of covalency than the iridium(III)-carbon bonds. In contrast to 2, the metalated carbon atom of 9 undergoes the addition of a proton of methanol to give [IrH2{¿2-N, N-(bipy)}(PiPr3)2]BF4 (12).

Idioma: Inglés

DOI: 10.1021/acs.organomet.0c00156

Año: 2020

Publicado en: Organometallics 39, 11 (2020), 2102-2115
ISSN: 0276-7333

Factor impacto JCR: 3.876 (2020)

Categ. JCR: CHEMISTRY, ORGANIC rank: 13 / 57 = 0.228 (2020) - Q1 - T1
Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 11 / 45 = 0.244 (2020) - Q1 - T1

Factor impacto SCIMAGO: 1.231 - Inorganic Chemistry (Q1) - Physical and Theoretical Chemistry (Q1) - Organic Chemistry (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E06-20R
Financiación: info:eu-repo/grantAgreement/ES/DGA/FEDER
Financiación: info:eu-repo/grantAgreement/ES/DGA/FSE
Financiación: info:eu-repo/grantAgreement/ES/DGA/LMP148-18

Tipo y forma: Article (PostPrint)

Área (Departamento): Área Química Inorgánica (Dpto. Química Inorgánica)