Catalytic H/D Exchange of Aluminium Hydrides through reversible formation of Cobalt–Aluminium Complexes

Here we present the catalytic deuteration of aluminium hydrides promoted by a cobalt(I) hydride complex. This simple yet effective method can be applied to a series of β-diketiminate stabilised aluminium dihydrides and appears to be synthetically widely relevant given the frequent utilisation of these reagents. Reactions are typically performed at 80-100 °C in presence of 5 mol% of the cobalt catalyst using benzene-d6 or D2 as deuterium source. After reaction times of 18-24 h deuterium incorporations of >95 % into the Al–H bonds are obtained. Key to this reactivity is the reversible formation of well-defined bimetallic cobalt–aluminium complexes some of which have been isolated and structurally characterised by single crystal X-ray diffraction. Computational analysis (DFT, QTAIM, LMO analysis) provides insight into the bonding of these bimetallic species as well as into the underlying mechanism of this unique H/D exchange process.