Osmium Catalysts for Acceptorless and Base-Free Dehydrogenation of Alcohols and Amines: Unusual Coordination Modes of a BPI Anion

Buil Juan, María Luisa (Universidad de Zaragoza) ; Esteruelas, Miguel. A. ; Gay, M. Pilar. ; Gómez-Gallego, Mar ; Nicasio A. I. ; Oñate, E. ; Santiago, A. ; Sierra, Miguel A.

Resumen: A novel type of catalyst precursors for the dehydrogenation of hydrogen carriers based on organic liquids has been discovered. Complexes OsH6(PiPr3)2 (1) and OsH(OH)(CO)(PiPr3)2 (2) react with 1,3-bis(6'-methyl-2'-pyridylimino)isoindoline (HBMePI) to give OsH3{¿2-Npy,Nimine-(BMePI)}(PiPr3)2 (3) and OsH{¿2-Npy,Nimine-(BMePI)}(CO)(PiPr3)2 (4). The unprecedented ¿2-Npy,Nimine coordination mode of BMePI is thermodynamically preferred with Os(IV) and Os(II) metal fragments and allows for preparation of BMePI-based dinuclear metal cations. Treatment of OsH2Cl2(PiPr3)2 (5) with 0.5 equiv of HBMePI in the presence of KOtBu affords the chloride salt of the bis(osmium(IV)) dinuclear cation [{OsH3(PiPr3)2}2{µ-(¿2-Npy,Nimine)2-BMePI}]+ (6). Related homoleptic bis(osmium(II)) complexes have been also synthesized. Complex 4 reacts with the bis(solvento) [OsH(CO){¿1-O-[OCMe2]2}(PiPr3)2]BF4 to give [{OsH(CO)(PiPr3)2}2{µ-(¿2-Npy,Nimine)2-BMePI}]BF4 (7), whereas the addition of 0.5 equiv of HBMePI to {OsCl(¿6-C6H6)}2(µ–Cl)2 (8) affords [{OsCl(¿6-C6H6)}2{µ-(¿2-Npy,Nimine)2-BMePI}]Cl (9). The reactions of 4 with 8 and {OsCl(¿6-p-cymene)}2(µ–Cl)2 (10) lead to the heteroleptic cations [(PiPr3)2(CO)HOs{µ-(¿2-Npy,Nimine)2-BMePI}OsCl(¿6-arene)]+ (arene = C6H6 (11), p-cymene (12)). The electronic structrure and electrochemical properties of the dinuclear complexes were also studied. Complexes 3 and 4 are efficient catalyst precursors for the acceptorless and base-free dehydrogenation of secondary and primary alcohols and cyclic and lineal amines. The primary alcohols afford aldehydes. The amount of H2 released per gram of heterocycle depends upon the presence of a methyl group adjacent to the nitrogen atom, the position of the nitrogen atom in the heterocycle, and the size of the heterocycle.

Idioma: Inglés

DOI: 10.1021/acs.organomet.7b00906

Año: 2018

Publicado en: Organometallics 37, 4 (2018), 603-617
ISSN: 0276-7333

Factor impacto JCR: 4.1 (2018)

Categ. JCR: CHEMISTRY, ORGANIC rank: 11 / 57 = 0.193 (2018) - Q1 - T1
Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 5 / 45 = 0.111 (2018) - Q1 - T1

Factor impacto SCIMAGO: 1.473 - Inorganic Chemistry (Q1) - Physical and Theoretical Chemistry (Q1) - Organic Chemistry (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E35
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2016-81797-REDC
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2017-82935-P

Tipo y forma: Article (PostPrint)

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