Tuning the pyridone scaffold within a Rhodium-NHC platform for gem-specific alkyne dimerization via a ligand-assisted proton shuttle mechanism

Español-Sánchez, Belinda ; Galiana-Cameo, María (Universidad de Zaragoza) ; Urriolabeitia, Asier (Universidad de Zaragoza) ; Polo, Victor (Universidad de Zaragoza) ; Passarelli, Vincenzo ; Pérez-Torrente, Jesús J. (Universidad de Zaragoza) ; Castarlenas, Ricardo

Resumen: A series of mononuclear square-planar Rh{κ2N,O-BHetA}(η2-coe)(NHC) (BHetA = Bis-Heteroatomic Acidato) complexes have been prepared. Modifications of the pyridonato BHetA-type ligand architecture include 4-Me, 5-Me, 6-Me, 3-Br, 4-Br, 4-OMe, and 5-NO2 substitutions as well as pyrimidonato, succinimidato, and 2-piperidonato catalysts. Two structural isomers have been observed for the complexes, depending on the stereoelectronic properties of the ligand. The structure–activity relationship has been studied for gem-specific alkyne dimerization via a cooperative ligand-assisted proton shuttle mechanism. Density functional theory calculations have revealed a mechanistic pathway involving the hemilabile coordination of the BHetA ligand, CMD deprotonation, π-alkyne protonation, and reductive elimination. The increase in oxygen basicity imparted by the substituent in the pyridonato ligand is key, the 4-methyl derivative being the most active catalyst. However, a favored iminol–amide tautomerization precludes an increase in catalytic activity for the more basic saturated piperidonato catalyst.

Idioma: Inglés

DOI: 10.1021/acs.organomet.4c00409

Año: 2024

Publicado en: Organometallics 43, 22 (2024), 2951-2962
ISSN: 0276-7333

Financiación: info:eu-repo/grantAgreement/ES/DGA/E42-23R
Financiación: info:eu-repo/grantAgreement/ES/MECD/FPU17-05417
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2019-103965GB-I00/AEI/10.13039/501100011033
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2022-137208NB-I00

Tipo y forma: Article (PostPrint)

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