"Contacted" vs "separated" aluminyls: Dynamic alkali metal effects in H2 activation

05 October 2022, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

This work discloses an unprecedented dynamic ion-pairing behaviour of "naked" aluminyl anions related to their stability and reactivity in solution. Rapid exchange between charge-separated and contacted species of the aluminyl anion [(BDI’)AlI]– (BDI’ = H2C=C(NAr)-C(H)=C(Me)-NAr; Ar = 2,6-iPr2C6H3) occurs in solution with [(L)M]+ counterions (M = Cs, K). While the two-dimensional polyether 18-crown-6 (L) favours the formation of persistent contacted species, the three-dimensional 2.2.2-cryptand ligand allows facile exchange. These aluminyl processes are experimentally probed by NMR spectroscopy, including DOSY NMR, and X-ray crystallography, which provide intimate details of the ion-pairing reversibility and ionic separations. The lability in these aluminyls is important for their stability and reactivity with the non-polar H2.

Keywords

aluminium
aluminyl anion
caesium
potassium
dihydrogen activation

Supplementary materials

Title
Description
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Title
Supporting Information
Description
Experimental procedures and characterisation data for all new compounds, including crystallographic data in CIF format (CCDC deposition numbers: 2205103, 2205104, 2205105, 2205106, 2205107 and 2205559).
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Supplementary deposited crystallographic files (CIF)
Description
Supplementary deposited crystallographic files (CIF).
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