Quantitative Determination of Active Species Transforming the R-NHC Coupling Process under Catalytic Conditions

Quantitative Determination of Active Species Transforming the R-NHC Coupling Process under Catalytic Conditions Full article

Journal

Inorganic Chemistry
ISSN: 0020-1669 , E-ISSN: 1520-510X

Output data

Year: 2024, Volume: 63, Number: 6, Pages: 2967-2976 Pages count : 10 DOI: 10.1021/acs.inorgchem.3c03614

Authors

Patil Ekaterina D. ¹ , Burykina Julia V. ¹ , Eremin Dmitry B. ¹ , Boiko Daniil A. ¹ , Shepelenko Konstantin E. ² , Ilyushenkova Valentina V. ¹ , Chernyshev Victor M. ² , Ananikov Valentine P. ^2,1

Affiliations

1	Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow 119991, Russia
2	Platov South-Russian State Polytechnic University (NPI), Prosveschenya 132, Novocherkassk 346428, Russia

Palladium complexes with N-heterocyclic carbenes (Pd/NHC) serve as prominent precatalysts in numerous Pd-catalyzed organic reactions. While the evolution of Pd/NHC complexes, which involves the cleavage of the Pd–C(NHC) bond via reductive elimination and dissociation, is acknowledged to influence the catalysis mechanism and the performance of the catalytic systems, conventional analytic techniques [such as NMR, IR, UV–vis, gas chromatography–mass spectrometry (GC–MS), and high-performance liquid chromatography (HPLC)] frequently fail to quantitatively monitor the transformations of Pd/NHC complexes at catalyst concentrations typical of real-world conditions (below approximately 1 mol %). In this study, for the first time, we show the viability of using electrospray ionization mass spectrometry (ESI-MS). This approach was combined with the use of selectively deuterated H-NHC, Ph-NHC, and O-NHC coupling products as internal standards, allowing for an in-depth quantitative analysis of the evolution of Pd/NHC catalysts within actual catalytic systems. The reliability of this approach was affirmed by aligning the ESI-MS results with the NMR spectroscopy data obtained at greater Pd/NHC precatalyst concentrations (2–5 mol %) in the Mizoroki–Heck, Sonogashira, and alkyne transfer hydrogenation reactions. The efficacy of the ESI-MS methodology was further demonstrated through its application in the Mizoroki–Heck reaction at Pd/NHC loadings of 5, 0.5, 0.05, and 0.005 mol %. In this work, for the first time, we present a methodology for the quantitative characterization of pivotal catalyst transformation processes commonly observed in M/NHC systems.

Patil E.D. , Burykina J.V. , Eremin D.B. , Boiko D.A. , Shepelenko K.E. , Ilyushenkova V.V. , Chernyshev V.M. , Ananikov V.P.
Quantitative Determination of Active Species Transforming the R-NHC Coupling Process under Catalytic Conditions
Inorganic Chemistry. 2024. V.63. N6. P.2967-2976. DOI: 10.1021/acs.inorgchem.3c03614 WOS Scopus OpenAlex

Web of science:	WOS:001161233100001
Scopus:	2-s2.0-85184826355
OpenAlex:	W4391338591

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