Mechanistic basis for tuning iridium hydride photochemistry from H2 evolution to hydride transfer hydrodechlorination.
Chem Sci
; 11(25): 6442-6449, 2020 Mar 06.
Article
em En
| MEDLINE
| ID: mdl-34094109
ABSTRACT
The photochemistry of metal hydride complexes is dominated by H2 evolution, limiting access to reductive transformations based on photochemical hydride transfer. In this article, the innate H2 evolution photochemistry of the iridium hydride complexes [Cp*Ir(bpy-OMe)H]+ (1, bpy-OMe = 4,4'-dimethoxy-2,2'-bipyridine) and [Cp*Ir(bpy)H]+ (2, bpy = 2,2'-bipyridine) is diverted towards photochemical hydrodechlorination. Net hydride transfer from 1 and 2 to dichloromethane produces chloromethane with high selectivity and exceptional photochemical quantum yield (Φ ≤ 1.3). Thermodynamic and kinetic mechanistic studies are consistent with a non-radical-chain reaction sequence initiated by "self-quenching" electron transfer between excited state and ground state hydride complexes, followed by proton-coupled electron transfer (PCET) hydrodechlorination that outcompetes H-H coupling. This unique photochemical mechanism provides a new hope for the development of light-driven hydride transfer reactions.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Chem Sci
Ano de publicação:
2020
Tipo de documento:
Article