Crystalline Anions Based on Classical N-Heterocyclic Carbenes

Merschel, Arne; Rottschäfer, Dennis; Neumann, Beate; Stammler, Hans-Georg; Ringenberg, Mark; van Gastel, Maurice; Demirer, Ilgin; Andrada, Diego M.; Ghadwal, Rajendra S.

doi:10.1002/anie.202215244

Item

ITEM ACTIONSEXPORT

Add to Basket

Local TagsRelease HistoryDetailsSummary

Released

Journal Article

Crystalline Anions Based on Classical N-Heterocyclic Carbenes

MPS-Authors

/persons/resource/persons216842

van Gastel, Maurice
Research Group van Gastel, Max-Planck-Institut für Kohlenforschung, Max Planck Society;

External Resource

No external resources are shared

Fulltext (restricted access)

There are currently no full texts shared for your IP range.

Fulltext (public)

There are no public fulltexts stored in PuRe

Supplementary Material (public)

There is no public supplementary material available

Citation

Merschel, A., Rottschäfer, D., Neumann, B., Stammler, H.-G., Ringenberg, M., van Gastel, M., et al. (2023). Crystalline Anions Based on Classical N-Heterocyclic Carbenes. Angewandte Chemie International Edition, 62(5): e202215244. doi:10.1002/anie.202215244.

Cite as: https://hdl.handle.net/21.11116/0000-000C-2043-4

Abstract

Herein, the first stable anions K[SIPr^Bp] (4 a-K) and K[IPr^Bp] (4 b-K) (SIPr^Bp=BpC{N(Dipp)CH₂}₂, IPr^Bp=BpC{N(Dipp)CH}₂; Bp=4-PhC₆H₄; Dipp=2,6-iPr₂C₆H₃) derived from classical N-heterocyclic carbenes (NHCs) (i.e. SIPr and IPr) have been isolated as violet crystalline solids. 4 a-K and 4 b-K are prepared by KC₈ reduction of the neutral radicals [SIPr^Bp] (3 a) and [IPr^Bp] (3 b), respectively. The radicals 3 a and 3 b as well as [Me-IPr^Bp] 3 c (Me-IPr^Bp=BpC{N(Dipp)CMe}₂) are accessible as crystalline solids on treatment of the respective 1,3-imidazoli(ni)um bromides (SIPr^Bp)Br (2 a), (IPr^Bp)Br (2 b), and (Me−IPr^Bp)Br (2 c) with KC₈. The cyclic voltammograms of 2 a–2 c exhibit two one-electron reversible redox processes in −0.5 to −2.5 V region that correspond to the radicals 3 a–3 c and the anions (4 a–4 c)⁻. Computational calculations suggest a closed-shell singlet ground state for (4 a–4 c)⁻ with the singlet-triplet energy gap of 17–24 kcal mol⁻¹.