σ-Hole interactions in organometallic catalysts: the case of methyltrioxorhenium(VII).
Dalton Trans
; 52(4): 1030-1035, 2023 Jan 24.
Article
em En
| MEDLINE
| ID: mdl-36602028
ABSTRACT
Methyltrioxorhenium(VII) (MTO) is a widely employed catalyst for metathesis, olefination, and most importantly, oxidation reactions. It is often preferred to other oxometal complexes due to its stability in air and higher efficiency. The seminal papers of K. B. Sharpless showed that when pyridine derivatives are used as co-catalysts, MTO-catalyzed olefin epoxidation with H2O2 as oxidant, a particularly useful reaction, is accelerated, with pyridine speeding up catalytic turnover and increasing the lifetime of MTO under the reaction conditions. In this paper, combined experimental and theoretical results show that the occurrence of σ-hole interactions in catalytic systems extends to MTO. Four crystalline adducts between MTO and aliphatic and heteroaromatic bases are obtained, and their X-ray analyses display short Reâ¯N/O contacts opposite to both O-Re and C-Re covalent bonds with geometries consistent with σ-hole interactions. Computational analyses support the attractive nature of these close contacts and confirm that their features are typical of σ-hole interactions. The understanding of the nature of Reâ¯N/O interactions may help to optimize the ligand-acceleration effect of pyridine in the epoxidation of olefins under MTO catalysis.
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Base de dados:
MEDLINE
Assunto principal:
Compostos Organometálicos
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Peróxido de Hidrogênio
Idioma:
En
Ano de publicação:
2023
Tipo de documento:
Article