Reactivity studies and structural outcomes of a bulky dialkylaluminium amide in the presence of the N-Heterocyclic Carbene, ItBu

Victoria A. Pollard, Maria-ngeles Fuentes, Stuart D. Robertson, Catherine Weetman, Alan R. Kennedy, Josh Brownlie, Fraser J. Angus, Cooper Smylie, Robert E. Mulvey

Research output: Contribution to journalArticlepeer-review

Abstract

Aluminium reagent iBu2Al(TMP) (TMP is 2,2,6,6-tetramethylpiperidide) has previously shown interesting synergistic metallation chemistry when paired with alkali metal amides. Here its structural chemistry and reactivity is explored in the presence of the N-heterocyclic carbene, ItBu, 1,3-di-tert-butylimidazol-2-ylidene. Abnormal aItBu structures are obtained with iBu2Al(TMP) on its own and in the co-presence of LiTMP, NaTMP or KTMP. Reaction with phenol is stoichiometric dependent leading to the diphenolate [ItBu(H)]+ [(PhO)2Al(iBu)2 and triphenolate [ItBu(H)]+ [(PhO)3Al(iBu)- ionic complexes. Dinuclear aItBu(Ph)C=N[Al(iBu)2N=C(TMP)Ph]Al(iBu)2 was the surprising product from reaction with benzonitrile, displaying an imidoC- and (iBu)2Al- disubstituted imidazolium ring as well as a second imido unit made by addition of "non-nucleophilic" TMP across the benzonitrile triple bond. Potential insight into the mechanism of this intriguing complicated reaction was gained through the crystallographic characterisation of the ketamide [iBu2AlN=C(Ph)TMP]2, a possible intermediate. Reaction with Ph2CHCN, diphenylacetonitrile, proved more straightforward affording the ionic complex [ItBu(H)]+ [Ph2C=C=N]-.
Original languageEnglish
Number of pages24
JournalPolyhedron
Publication statusAccepted/In press - 6 Sep 2021

Keywords

  • abnormal carbene
  • alkali-metal
  • N-heterocyclic carbene
  • NMR studies
  • organoaluminium compound

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