Frustrated Lewis Pairs from Al–E{14} Bonds (E{14} = Ge, Sn, Pb)

George Smith, Samuel E. Neale, Matthew J. Evans, Xuning Li, Junhu Wang, Michael G. Gardiner, Claire L. McMullin, Robin Fulton, Martyn P. Coles

Research output: Contribution to journalArticlepeer-review

Abstract

The potassium aluminyl K[Al(NON)] ([NON] 2−=[O(SiMe 2NDipp) 2] 2−, Dipp=2,6-iPr 2C 6H 3) reacts with group 14 chloroamidinates E {14}(Am)Cl (E {14}=Ge, Sn, Pb. [Am] =[tBuC(NDipp) 2] ) to form (NON)Al−E {14}(Am) Lewis pairs with unsupported Al−E {14} bonds, including the first structurally authenticated Al−Pb bond. Analysis using spectroscopic (NMR, UV-vis and Mössbauer for E {14}=Sn), X-ray diffraction and computational (DFT, QTAIM, TD-DFT) methods conclude an Al−E {14} σ-bond derived from a Lewis basic Al and a Lewis acidic tetrylene, with back-donation from the E {14} s-orbital lone pair donor NBO to acceptor NBOs on Al that are derived from s/p-orbitals. The reaction of the Al−Ge compound with CO 2 forms the dioxocarbene (NON)Al(μ-O 2C)Ge(Am), whilst under the same conditions the Al−Sn compound reacts with additional CO 2 to form the carbonate, (NON)Al(μ-CO 3)Sn(Am). Addition of ethene to the Al−E {14} (E {14}=Ge, Sn) compounds introduces an ethylene bridge between the aluminium and group 14 atoms forming a frustrated Lewis pair (FLP). Reaction of the (Al/Ge) FLP with CO 2 forms an activation product with new Al−O and Ge−C bonds, whilst reaction with iPrN=C=NiPr proceeds with insertion into the Al−C bond to form an aluminium amidinate.

Original languageEnglish
Article numbere202404206
JournalChemistry - A European Journal
Volume31
Issue number7
Early online date4 Dec 2024
DOIs
Publication statusPublished - 3 Feb 2025

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Acknowledgements

We acknowledge experiments by Dr Simon Granville and Prof Nick Cox who examined compound 1 c using SQUID magnetometry and EPR spectroscopy, respectively, concluding that there is no appreciable radical character. The authors gratefully acknowledge the University of Bath’s Research Computing Group (http://doi.org/10.15125/b6cd-s854) for their support in this work

Keywords

  • CO activation
  • aluminyl
  • frustrated Lewis pair (FLP)
  • heterobimetallic
  • tetrylene

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Organic Chemistry

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