Hypothetical heterocyclic carbenes
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Brian F. Yates
Abstract
Density functional theory is used to explore the geometries and properties of 55 heterocyclic carbenes containing N, P, As, Sb, Bi, O, S, Se, Te and Po. Planar and non-planar structures have been systematically evaluated and a variety of measures (including Wiberg bond indices, orbital occupancies, HOMO–LUMO gaps, proton affinities, J(13C–1H) coupling constants and isodesmic reaction energies) have been considered for all systems. The main conclusions are that the heavier heteroatoms can be effective π-donors towards the carbene carbon if planarity can be attained, and that the cost of attaining this planarity is actually quite low for the majority of the heterocyclic carbenes considered.
Funding source: Australian Research Council
Award Identifier / Grant number: DP180100904
Acknowledgments
This research was supported by the University of Tasmania high performance computing facility and a grant from the Australian Research Council.
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Research ethics: Not applicable.
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Informed consent: Not applicable.
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Author contributions: The author has accepted responsibility for the entire content of this manuscript and approved its submission.
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Use of Large Language Models, AI and Machine Learning Tools: None declared.
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Conflict of interest: The author states no conflict of interest.
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Research funding: This study was supported by the Australian Research Council through grant number DP180100904.
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Data availability: Data is available in the Supplementary Material accompanying this manuscript.
References
1. Arduengo, A. J.; Harlow, R. L.; Kline, M. A Stable Crystalline Carbene. J. Am. Chem. Soc. 1991, 113, 361–363; https://doi.org/10.1021/ja00001a054.Suche in Google Scholar
2. Heinemann, C.; Muller, T.; Apeloig, Y.; Schwarz, H. On the Question of Stability, Conjugation and “Aromaticity” in Imidazol-2-Ylidenes and Their Silicon Analogs. J. Am. Chem. Soc. 1996, 118, 2023–2038; https://doi.org/10.1021/ja9523294.Suche in Google Scholar
3. Boehme, C.; Frenking, G. Electronic Structure of Stable Carbenes, Silylenes and Germylenes. J. Am. Chem. Soc. 1996, 118, 2039–2046; https://doi.org/10.1021/ja9527075.Suche in Google Scholar
4. Melaimi, M.; Soleilhavoup, M.; Bertrand, G. Stable Cyclic Carbenes and Related Species beyond Diaminocarbenes. Angew. Chem., Int. Ed. 2010, 49, 8810–8849; https://doi.org/10.1002/anie.201000165.Suche in Google Scholar PubMed PubMed Central
5. Nelson, D. J.; Nolan, S. P. N-heterocyclic Carbenes. In In N-Heterocyclic Carbenes: Effective Tools for Organometallic Synthesis; Nolan, S. P., Ed.; Wiley VCH: Weinheim, 2014; pp. 1–24.10.1002/9783527671229.ch01Suche in Google Scholar
6. Jahnke, M. C.; Hahn, F. E. Introduction to N-Heterocyclic Carbenes: Synthesis and Stereoelectronic Parameters. In In N-Heterocyclic Carbenes: From Laboratory Curiosities to Efficient Synthetic Tools; Díez-González, S., Ed.; Royal Society of Chemistry: Cambridge, 2017; pp. 1–45.10.1039/9781782626817-00001Suche in Google Scholar
7. Bellotti, P.; Koy, M.; Hopkinson, M. N.; Glorius, F. Recent Advances in the Chemistry and Applications of N-Heterocyclic Carbenes. Nat. Rev. Chem. 2021, 5, 711–725; https://doi.org/10.1038/s41570-021-00321-1.Suche in Google Scholar PubMed
8. Magill, A. M.; Cavell, K. J.; Yates, B. F. Basicity of Nucleophilic Carbenes in Aqueous and Nonaqueous Solvents – Theoretical Predictions. J. Am. Chem. Soc. 2004, 126, 8717–8724; https://doi.org/10.1021/ja038973x.Suche in Google Scholar PubMed
9. Magill, A. M.; Yates, B. F. An Assessment of Theoretical Protocols for Calculation of the pKa Values of the Prototype Imidazolium Cation. Aust. J. Chem. 2004, 57, 1205–1210; https://doi.org/10.1071/ch04159.Suche in Google Scholar
10. Graham, D. C. The Influence of Heteroatom Substitution on Heterocyclic Carbenes and their Complexes. PhD Thesis; University of Tasmania: Hobart, Australia, 2003.Suche in Google Scholar
11. Graham, D. C.; Yates, B. F. Increased Stability of NO and NS Heterocyclic Carbenes? Aust. J. Chem. 2004, 57, 359–364; https://doi.org/10.1071/ch03248.Suche in Google Scholar
12. Graham, D. C.; Cavell, K. J.; Yates, B. F. Dimerization Mechanisms of Heterocyclic Carbenes. J. Phys. Org. Chem. 2005, 18, 298–309; https://doi.org/10.1002/poc.846.Suche in Google Scholar
13. Hollóczki, O.; Kelemen, Z.; Nyulászi, L. On the Organocatalytic Activity of N-Heterocyclic Carbenes: Role of Sulfur in Thiamine. J. Org. Chem. 2012, 77, 6014–6022; https://doi.org/10.1021/jo300745e.Suche in Google Scholar PubMed
14. Kelemen, Z.; Hollóczki, O.; Oláh, J.; Nyulászi, L. Oxazol-2-ylidenes. A New Class of Stable Carbenes? RSC Adv. 2013, 3, 7970–7978; https://doi.org/10.1039/c3ra41177j.Suche in Google Scholar
15. Ramsden, C. A.; Oziminski, W. P. A Quantitative Analysis of Factors Influencing Ease of Formation and σ-Bonding Strength of Oxa- and Thia-N-Heterocyclic Carbenes. J. Org. Chem. 2017, 82, 12485–12491; https://doi.org/10.1021/acs.joc.7b02283.Suche in Google Scholar PubMed
16. Ritch, J. S. Chalcogen-Substituted Carbenes: A Density Functional Study of Structure, Stability and Donor Ability. RSC Adv. 2023, 13, 16828–16836; https://doi.org/10.1039/d3ra03324d.Suche in Google Scholar PubMed PubMed Central
17. Kuhn, N.; Kratz, T. Synthesis of Imidazol-2-Ylidenes by Reduction of Imidazole-2(3H)-Thiones. Synthesis 1993, 1993, 561–562; https://doi.org/10.1055/s-1993-25902.Suche in Google Scholar
18. Arduengo, A. J.; Goerlich, J. R.; Marshall, W. J. A Stable Thiazol-2-Ylidene and its Dimer. Liebigs Ann 1997, 1997, 365–374; https://doi.org/10.1002/jlac.199719970213.Suche in Google Scholar
19. Hahn, F. E.; Tamm, M.; Lügger, T. Equilibrium between Isocyanide and Carbene Complexes in Coordination Compounds of 2,6-Dihydroxyphenyl Isocyanide. Angew. Chem., Int. Ed. Engl. 1994, 33, 1356–1359; https://doi.org/10.1002/anie.199413561.Suche in Google Scholar
20. Fekete, A.; Nyulászi, L. Phosphorous Stabilized Carbenes: Theoretical Predictions. J. Organomet. Chem. 2002, 643-644, 278–284.10.1016/S0022-328X(01)01222-0Suche in Google Scholar
21. Jacobsen, H. Bonding Aspects of P-Heterocyclic Carbene Transition Metal Complexes. A Computational Assessment. J. Organomet. Chem. 2005, 690, 6068–6078; https://doi.org/10.1016/j.jorganchem.2005.07.112.Suche in Google Scholar
22. Schoeller, W. W.; Schroeder, D.; Rozhenko, A. B. On the Ligand Properties of the P- versus the N-Heterocyclic Carbene for a Grubbs Catalyst in Olefin Metathesis. J. Organomet. Chem. 2005, 690, 6079–6088; https://doi.org/10.1016/j.jorganchem.2005.08.001.Suche in Google Scholar
23. Al Furaiji, K. H. M.; Iversen, K. J.; Dutton, J. L.; Wilson, D. J. D. Theoretical Investigation of Hydride Insertion into N-Heterocyclic Carbenes Containing N, P, C, O and S Heteroatoms. Chem.–Asian J. 2018, 13, 3745–3752; https://doi.org/10.1002/asia.201801285.Suche in Google Scholar PubMed
24. Kapp, J.; Schade, C.; El-Nahasa, A. M.; Schleyer, P. V. R. Heavy Element π Donation Is Not Less Effective. Angew Chem. Int. Ed. Engl. 1996, 35, 2236–2238; https://doi.org/10.1002/anie.199622361.Suche in Google Scholar
25. Sobel, D. The Elements of Marie Curie; 4th Estate: London, UK, 2024.Suche in Google Scholar
26. Gupta, R.; Frison, G. Correlation between NMR Coupling Constants and σ-Donating Properties of N-Heterocyclic Carbenes and Their Derivatives. Chem. Eur. J. 2025, 31, e202403403; https://doi.org/10.1002/chem.202403403.Suche in Google Scholar PubMed
27. Huynh, H. V. Electronic Properties of N-Heterocyclic Carbenes and Their Experimental Determination. Chem. Rev. 2018, 118, 9457–9492; https://doi.org/10.1021/acs.chemrev.8b00067.Suche in Google Scholar PubMed
28. Yaqoob, M.; Abbasi, M.; Anwar, H.; Iqbal, J.; Asad, M.; Asiri, A. M.; Iqbal, M. A. Dative Behavior of N-Heterocyclic Carbenes (NHCs) with Selenium in Se-NHC Compounds. Rev. Inorg. Chem. 2022, 42, 229–238; https://doi.org/10.1515/revic-2021-0031.Suche in Google Scholar
29. Pruschinski, L.; Kahnert, S. R.; Herzberger, C.; Namyslo, J. C.; Schmidt, A. Studies on the Effect of Positive and Negative Charges on the 77Se NMR Shifts of Selenones and Selenyls of N-Heterocyclic Carbenes of Imidazolium-4,5-Dicarboxylates. J. Org. Chem. 2025, 9-0, 2201–2213.10.1021/acs.joc.4c02581Suche in Google Scholar PubMed PubMed Central
30. Nyulászi, L.; Veszpremi, T.; Forro, A. Stabilized Carbenes Do Not Dimerize. Phys. Chem. Chem. Phys. 2000, 2, 3127–3129; https://doi.org/10.1039/b003588m.Suche in Google Scholar
31. Kassaee, M. Z.; Shakib, F. A.; Momeni, M. R.; Ghambarian, M.; Musavi, S. M. Carbenes with Reduced Heteroatom Stabilization: A Computational Approach. J. Org. Chem. 2010, 75, 2539–2545; https://doi.org/10.1021/jo100022t.Suche in Google Scholar PubMed
32. Rezabal, E.; Frison, G. Estimating the π Binding Energy of N-Heterocyclic Carbenes: The Role of Polarisation. J. Comp. Chem. 2015, 36, 564–572; https://doi.org/10.1002/jcc.23852.Suche in Google Scholar PubMed
33. Gómez-Suárez, A.; Nelson, D. J.; Nolan, S. P. Quantifying and Understanding the Steric Properties of N-Heterocyclic Carbenes. Chem. Commun. 2017, 53, 2650–2660; https://doi.org/10.1039/c7cc00255f.Suche in Google Scholar PubMed
34. Masuda, J. D.; Martin, D.; Lyon-Saunier, C.; Baceiredo, A.; Gornitzka, H.; Donnadieu, B.; Bertrand, G. Stable P-Heterocyclic Carbenes: Scope and Limitations. Chem.–Asian J. 2007, 2, 178–187; https://doi.org/10.1002/asia.200600300.Suche in Google Scholar PubMed PubMed Central
35. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Petersson, G. A.; Nakatsuji, H.; Li, X.; Caricato, M.; Marenich, A. V.; Bloino, J.; Janesko, B. G.; Gomperts, R.; Mennucci, B.; Hratchian, H. P.; Ortiz, J. V.; Izmaylov, A. F.; Sonnenberg, J. L.; Williams-Young, D.; Ding, F.; Lipparini, F.; Egidi, F.; Goings, J.; Peng, B.; Petrone, A.; Henderson, T.; Ranasinghe, D.; Zakrzewski, V. G.; Gao, J.; Rega, N.; Zheng, G.; Liang, W.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Throssell, K.; Montgomery, J. A.Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M. J.; Heyd, J. J.; Brothers, E. N.; Kudin, K. N.; Staroverov, V. N.; Keith, T. A.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A. P.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Millam, J. M.; Klene, M.; Adamo, C.; Cammi, R.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Farkas, O.; Foresman, J. B.; Fox, D. J. Gaussian 16, Revision C.02. Gaussian, Inc.: Wallingford CT, 2019. https://gaussian.com/products/ (accessed 2025-06-18).Suche in Google Scholar
36. Cao, C.; Zhang, C.; Gu, J.; Mo, Y. Double-boron Heterocyclic Carbenes: A Computational Study of Diels-Alder Reactions. Phys. Chem. Chem. Phys. 2024, 26, 28082–28090; https://doi.org/10.1039/d4cp03615h.Suche in Google Scholar PubMed
37. Montgomery, J. A.; Frisch, M. J.; Ochterski, J. W.; Petersson, G. A. A Complete Basis Set Model Chemistry. VI. Use of Density Functional Geometries and Frequencies. J. Chem. Phys. 1999, 110, 2822–2827; https://doi.org/10.1063/1.477924.Suche in Google Scholar
38. Liptak, M. D.; Shields, G. C. Accurate pKa Calculations for Carboxylic Acids Using Complete Basis Set and Gaussian-N Models Combined with CPCM Continuum Solvation Methods. J. Am. Chem. Soc. 2001, 123, 7314–7319; https://doi.org/10.1021/ja010534f.Suche in Google Scholar PubMed
39. Weigend, F.; Ahlrichs, R. Balanced Basis Sets of Split Valence, Triple Zeta Valence and Quadruple Zeta Valence Quality for H to Rn: Design and Assessment of Accuracy. Phys. Chem. Chem. Phys. 2005, 7, 3297–3305; https://doi.org/10.1039/b508541a.Suche in Google Scholar PubMed
40. Chai, J.-D.; Head-Gordon, M. Long-range Corrected Hybrid Density Functionals with Damped Atom-Atom Dispersion Corrections. Phys. Chem. Chem. Phys. 2008, 10, 6615–6620; https://doi.org/10.1039/b810189b.Suche in Google Scholar PubMed
41. Marenich, A. V.; Cramer, C. J.; Truhlar, D. G. Universal Solvation Model Based on Solute Electron Density and a Continuum Model of the Solvent Defined by the Bulk Dielectric Constant and Atomic Surface Tensions. J. Phys. Chem. B 2009, 113, 6378–6396; https://doi.org/10.1021/jp810292n.Suche in Google Scholar PubMed
42. Wiberg, K. B. Application of the Pople-Santry-Segal CNDO Method to the Cyclopropylcarbinyl and Cyclobutyl Cation and to Bicyclobutane. Tetrahedron 1968, 24, 1083–1096; https://doi.org/10.1016/0040-4020(68)88057-3.Suche in Google Scholar
43. NBO Version 3.1; Glendening, E. D.; Reed, A. E.; Carpenter, J. E.; Weinhold, F.; Gaussian Inc.: Pittsburgh, PA, 2003.Suche in Google Scholar
44. Adamo, C.; Jacquemin, D. The Calculations of Excited-State Properties with Time-Dependent Density Functional Theory. Chem. Soc. Rev. 2013, 42, 845–856; https://doi.org/10.1039/c2cs35394f.Suche in Google Scholar PubMed
45. Sychrovsky, V.; Gräfenstein, J.; Cremer, D. Nuclear Magnetic Resonance Spin-Spin Coupling Constants from Coupled Perturbed Density Functional Theory. J. Chem. Phys. 2000, 113, 3530–3547.10.1063/1.1286806Suche in Google Scholar
46. Del Bene, J. E.; Elguero, J. Can Changes in One-Bond Spin-Spin Coupling Constants in Acids Be Related to Gas-phase Proton Affinities of Bases? J. Phys. Chem. A 2007, 111, 6443–6448; https://doi.org/10.1021/jp072145z.Suche in Google Scholar PubMed
Supplementary Material
This article contains supplementary material (https://doi.org/10.1515/pac-2025-0472).
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