AI Article Synopsis
- The low-valent ß-diketiminate complex (BDI)Al shows stability in benzene but can transform into (BDI)Al(Ph)H with the help of (BDI)CaH catalyst at 20 °C.
- Similar reactions also occur with toluene and p-xylene, with toluene displaying notable meta-selectivity for functionalization.
- Attempts to use Mg or Zn hydride catalysts were unsuccessful, leading to the formation of stable (BDI)Al(H)M(BDI) complexes instead of desired products, while DFT calculations suggest that Ca is crucial for efficient C-H bond activation.
Article Abstract
The low-valent ß-diketiminate complex ( BDI)Al is stable in benzene but addition of catalytic quantities of [( BDI)CaH] at 20 °C led to ( BDI)Al(Ph)H ( BDI=CH[C(CH )N-DIPP] , DIPP=2,6-diisopropylphenyl). Similar Ca-catalyzed C-H bond activation is demonstrated for toluene or p-xylene. For toluene a remarkable selectivity for meta-functionalization has been observed. Reaction of ( BDI)Al(m-tolyl)H with I gave m-tolyl iodide, H and ( BDI)AlI which was recycled to ( BDI)Al. Attempts to catalyze this reaction with Mg or Zn hydride catalysts failed. Instead, the highly stable complexes ( BDI)Al(H)M( BDI) (M=Mg, Zn) were formed. DFT calculations on the Ca hydride catalyzed arene alumination suggest that a similar but more loosely bound complex is formed: ( BDI)Al(H)Ca( BDI). This is in equilibrium with the hydride bridged complex ( BDI)Al(μ-H)Ca( BDI) which shows strongly increased electron density at Al. The combination of Ca-arene bonding and a highly nucleophilic Al center are key to facile C-H bond activation.
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Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6856855 | PMC |
| http://dx.doi.org/10.1002/anie.201908978 | DOI Listing |
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