A simple 1 H NMR method for determining the σ-donor properties of N-heterocyclic carbenes

Guangrong Meng, Lazaros Kakalis, Steven P. Nolan, Steven P. Nolan

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


The σ-donor properties of NHC ligands (NHC = N-heterocyclic carbene) are crucial in controlling their interaction with transition metals, and as a consequence, to determine the selectivity and reactivity of NHCs in transition-metal-catalysis. Herein, we report a simple NMR method for estimating the σ-donor properties of NHC ligands based on a straightforward 1H NMR measurement of ligand precursors. We present evaluation of σ-donating properties for a range of NHC ligands varied by structure and electronics that are relevant to transition-metal-catalysis. We expect that the simple measurement of σ-donating properties of NHCs, together with the known methods for evaluating sterics and π-backbonding, will enhance the understanding of the properties of NHCs in transition-metal-catalysis.
Original languageEnglish (US)
Pages (from-to)378-381
Number of pages4
JournalTetrahedron Letters
Issue number4
StatePublished - Jan 4 2019
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2022-06-09
Acknowledgements: Rutgers University and the NSF (CAREER CHE-1650766) are gratefully acknowledged for support. The Bruker 500 MHz spectrometer used in this study was supported by the NSF-MRI grant (CHE-1229030). G.M. thanks the Graduate-School-Newark for a Dissertation Fellowship. SPN gratefully acknowledges King Saud University, the European COST action CHAOS and VLAIO (SBO project CO2PERATE) for support. This study was partially supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.


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