Probing the Extremes of Covalency in M−Al bonds: Lithium and Zinc Aluminyl Compounds

Synthetic routes to lithium, magnesium, and zinc aluminyl complexes are reported, allowing for the first structural characterization of an unsupported lithium–aluminium bond. Crystallographic quantum-chemical studies consistent with presence a highly polar Li−Al interaction, characterized by low bond order relatively little charge transfer from Al Li. Comparison magnesium systems reveals changes both M−Al (NON)Al fragment (where NON=4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene), more covalent character, latter complex being shown react CO2 via pathway that implies centre acts as nucleophilic partner.