Donor-influenced structure-activity correlations in stoichiometric and catalytic reactions of lithium monoamido-monohydrido-dialkylaluminates

A series of heteroleptic monoamido-monohydrido dialkyl-aluminate complexes of general formula [iBu₂AlTMPHLi·donor] are synthesized and characterised in the solution and in the solid state. Applying these complexes in catalytic hydroboration reactions with representative aldehydes and ketones reveals that all are competent, however a definite donor substituent effect is discernible. The bifunctional nature of the complexes is also probed by assessing their performance in metallation of a triazole and phenylacetylene and addition across pyrazine. These results lead to an example of phenylacetylene hydroboration, which likely proceeds via deprotonation, rather than insertion as observed with the aldehydes and ketones. Collectively, the results emphasise that reactivity is strongly influenced by both the mixed-metal constitution and mixed-ligand constitution of the new aluminates.