Tricyanoborane-Functionalized Anionic N-Heterocyclic Carbenes: Adjustment of Charge and Stereo-Electronic Properties

Overview

Journal Chemistry

Specialty Chemistry

Date 2022 May 10

PMID 35535791

Authors

Ludwig Zapf

Sven Peters

Rudiger Bertermann

Udo Radius

Maik Finze

Affiliations

Soon will be listed here.

Abstract

The 1-methyl-3-(tricyanoborane)imidazolin-2-ylidenate anion (2) was obtained in high yield by deprotonation of the B(CN) -methylimidazole adduct 1. Regarding charge and stereo-electronic properties, anion 2 closes the gap between well-known neutral NHCs and the ditopic dianionic NHC, the 1,3-bis(tricyanoborane)imidazolin-2-ylidenate dianion (IIb). The influence of the number of N-bonded tricyanoborane moieties on the σ-donating and π-accepting properties of NHCs was assessed by quantum chemical calculations and verified by experimental data on 2, IIb, and 1,3-dimethylimidazolin-2-ylidene (IMe, IIa). Therefore NHC 2, which acts as a ditopic ligand via the carbene center and the cyano groups, was reacted with alkyl iodides, selenium, and [Ni(CO) ] yielding alkylated imidazoles 3 and 4, the anionic selenium adduct 5, and the anionic nickel tricarbonyl complex 8, respectively. The results of this study prove that charge, number of coordination sites, buried volume (%V ) and σ-donor and π-acceptor abilities of NHCs can be effectively fine-tuned via the number of tricyanoborane substituents.

Citing Articles

An easy-to-perform evaluation of steric properties of Lewis acids.

Zapf L, Riethmann M, Fohrenbacher S, Finze M, Radius U Chem Sci. 2023; 14(9):2275-2288.

PMID: 36873848 PMC: 9977453. DOI: 10.1039/d3sc00037k.

Tricyanoborane-Functionalized Anionic N-Heterocyclic Carbenes: Adjustment of Charge and Stereo-Electronic Properties.

Zapf L, Peters S, Bertermann R, Radius U, Finze M Chemistry. 2022; 28(39):e202200275.

PMID: 35535791 PMC: 9401011. DOI: 10.1002/chem.202200275.

References

Kolychev E, Kronig S, Brandhorst K, Freytag M, Jones P, Tamm M . Iridium(I) complexes with anionic N-heterocyclic carbene ligands as catalysts for the hydrogenation of alkenes in nonpolar media. J Am Chem Soc. 2013; 135(33):12448-59. DOI: 10.1021/ja406529c. View

Peris E . Smart N-Heterocyclic Carbene Ligands in Catalysis. Chem Rev. 2017; 118(19):9988-10031. DOI: 10.1021/acs.chemrev.6b00695. View

Mercs L, Albrecht M . Beyond catalysis: N-heterocyclic carbene complexes as components for medicinal, luminescent, and functional materials applications. Chem Soc Rev. 2010; 39(6):1903-12. DOI: 10.1039/b902238b. View

Bohrer H, Trapp N, Himmel D, Schleep M, Krossing I . From unsuccessful H2-activation with FLPs containing B(Ohfip)3 to a systematic evaluation of the Lewis acidity of 33 Lewis acids based on fluoride, chloride, hydride and methyl ion affinities. Dalton Trans. 2015; 44(16):7489-99. DOI: 10.1039/c4dt02822h. View

Asay M, Jones C, Driess M . N-heterocyclic carbene analogues with low-valent group 13 and group 14 elements: syntheses, structures, and reactivities of a new generation of multitalented ligands. Chem Rev. 2010; 111(2):354-96. DOI: 10.1021/cr100216y. View

Drisch M, Bischoff L, Sprenger J, Hennig P, Wirthensohn R, Landmann J . Innovative Syntheses of Cyano(fluoro)borates: Catalytic Cyanation, Electrochemical and Electrophilic Fluorination. Chemistry. 2020; 26(50):11625-11633. PMC: 7540003. DOI: 10.1002/chem.202002324. View

Hopkinson M, Richter C, Schedler M, Glorius F . An overview of N-heterocyclic carbenes. Nature. 2014; 510(7506):485-96. DOI: 10.1038/nature13384. View

Wang Y, Robinson G . N-heterocyclic carbene-main-group chemistry: a rapidly evolving field. Inorg Chem. 2014; 53(22):11815-32. DOI: 10.1021/ic502231m. View

Clavier H, Nolan S . Percent buried volume for phosphine and N-heterocyclic carbene ligands: steric properties in organometallic chemistry. Chem Commun (Camb). 2010; 46(6):841-61. DOI: 10.1039/b922984a. View

10.

Bourissou D, Guerret O, Gabbai F, Bertrand G . Stable Carbenes. Chem Rev. 2001; 100(1):39-92. DOI: 10.1021/cr940472u. View

11.

Junor G, Lorkowski J, Weinstein C, Jazzar R, Pietraszuk C, Bertrand G . The Influence of C(sp )H-Selenium Interactions on the Se NMR Quantification of the π-Accepting Properties of Carbenes. Angew Chem Int Ed Engl. 2020; 59(49):22028-22033. DOI: 10.1002/anie.202010744. View

12.

Kirmse W . The beginnings of N-heterocyclic carbenes. Angew Chem Int Ed Engl. 2010; 49(47):8798-801. DOI: 10.1002/anie.201001658. View

13.

Landmann J, Keppner F, Hofmann D, Sprenger J, Haring M, Zottnick S . Deprotonation of a Hydridoborate Anion. Angew Chem Int Ed Engl. 2017; 56(10):2795-2799. DOI: 10.1002/anie.201611899. View

14.

Kuhlman M, Yao H, Rauchfuss T . Synthesis and characterization of the hexagonal prismatic cage [THF[subset or is implied by][PhB(CN)(3)](6)[Cp*Rh](6)](6+). Chem Commun (Camb). 2004; (12):1370-1. DOI: 10.1039/b401505c. View

15.

Landmann J, Hennig P, Ignatev N, Finze M . Borylation of fluorinated arenes using the boron-centred nucleophile B(CN) - a unique entry to aryltricyanoborates. Chem Sci. 2017; 8(9):5962-5968. PMC: 5620525. DOI: 10.1039/c7sc02249b. View

16.

Krahfuss M, Nitsch J, Bickelhaupt F, Marder T, Radius U . N-Heterocyclic Silylenes as Ligands in Transition Metal Carbonyl Chemistry: Nature of Their Bonding and Supposed Innocence. Chemistry. 2020; 26(49):11276-11292. PMC: 7497151. DOI: 10.1002/chem.202001062. View

17.

Kerpen C, Sprenger J, Herkert L, Schafer M, Bischoff L, Zeides P . Protonation versus Oxonium Salt Formation: Basicity and Stability Tuning of Cyanoborate Anions. Angew Chem Int Ed Engl. 2017; 56(10):2800-2804. DOI: 10.1002/anie.201611901. View

18.

Martin C, Soleilhavoup M, Bertrand G . Carbene-Stabilized Main Group Radicals and Radical Ions. Chem Sci. 2013; 4(8):3020-3030. PMC: 3714118. DOI: 10.1039/C3SC51174J. View

19.

Frosch J, Koneczny M, Bannenberg T, Tamm M . Halogen Complexes of Anionic N-Heterocyclic Carbenes. Chemistry. 2020; 27(13):4349-4363. PMC: 7986712. DOI: 10.1002/chem.202004418. View

20.

Wong Y, Landmann J, Finze M, Bryce D . Dynamic Disorder and Electronic Structures of Electron-Precise Dianionic Diboranes: Insights from Solid-State Multinuclear Magnetic Resonance Spectroscopy. J Am Chem Soc. 2017; 139(24):8200-8211. DOI: 10.1021/jacs.7b01783. View