Abstract
N-heterocyclic carbene gold(I) chloride and hydroxide complexes are regularly used as synthons to access various oxygen-, nitrogen- or carbon-bound gold complexes. They are also widely employed as efficient catalysts in addition reactions of hydroelements to unsaturated bonds and in several rearrangement and decarboxylation protocols. Here we describe the multigram synthesis of the most common mononuclear N-heterocyclic carbene gold(I) chloride complexes bearing the N,N′-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes), N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) and N,N′-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)imidazol-2-ylidene (IPr*) ligands. Their synthesis is achieved through the straightforward and practical weak base approach in a total time of 4–5 h. This straightforward methodology is conducted under air and possesses considerable advantages over alternative routes, such as the use of a sustainable reaction solvent, minimal amounts of a mild base and commercially available or easily obtained starting materials. Additionally, we describe the synthesis of the mononuclear gold(I) hydroxide complex bearing the IPr ligand, using the state-of-the-art method requiring 24 h. Finally, the improved synthesis of the dinuclear gold(I) hydroxide complex [{Au(IPr)}2(μ-OH)][BF4] is described (~3 h). All procedures can be performed by researchers with standard training and lead to high yields (76–99%) of microanalytically pure bench-stable materials.
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Acknowledgements
We are grateful to VLAIO (SBO project CO2PERATE). The Special Research Fund of Ghent University is acknowledged for a doctoral scholarship (01D14919) to N.V.T., as well as starting and project grants to S.P.N. The Research Foundation–Flanders is also gratefully acknowledged for a Fundamental Research PhD fellowship to N.V.T. (11I6921N).
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F.N., N.V.T., A.C. and S.P.N. were involved in the design and optimization of the procedures described here. The manuscript was assembled and edited by all authors.
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Key references using this protocol
Collado, A. et al. Chem. Commun. 49, 5541–5543 (2013): https://doi.org/10.1039/C3CC43076F
Nahra, F. et al. Polyhedron 84, 59–62 (2014): https://doi.org/10.1016/j.poly.2014.06.017
Gaillard, S. et al. Chem. Commun. 46, 2742–2744 (2010): https://doi.org/10.1039/C0CC00018C
Gaillard, S. et al. Chem. Eur. J. 16, 13729–13740 (2010): https://doi.org/10.1002/chem.201001688
Key data used in this protocol
Collado, A. et al. Chem. Commun. 49, 5541–5543 (2013): https://doi.org/10.1039/C3CC43076F
Nahra, F. et al. Polyhedron 84, 59–62 (2014): https://doi.org/10.1016/j.poly.2014.06.017
Gaillard, S. et al. Chem. Eur. J. 16, 13729–13740 (2010): https://doi.org/10.1002/chem.201001688
Gómez-Suárez, A. et al. Organometallics 32, 1106–1111 (2013): https://doi.org/10.1021/om301249r
Marion, N. et al. J. Am. Chem. Soc. 131, 448–449 (2009): https://doi.org/10.1021/ja809403e
Nun, P. et al. J. Organomet. Chem. 696, 7–11 (2011): https://doi.org/10.1016/j.jorganchem.2010.08.052
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Supplementary Data 1
Raw NMR data for Complex 8 and IR data for Complexes 7 and 8
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Nahra, F., Tzouras, N.V., Collado, A. et al. Synthesis of N-heterocyclic carbene gold(I) complexes. Nat Protoc 16, 1476–1493 (2021). https://doi.org/10.1038/s41596-020-00461-6
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DOI: https://doi.org/10.1038/s41596-020-00461-6
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