Probing the Extremes of Covalency in M−Al bonds: Lithium and Zinc Aluminyl Compounds
Matthew M. D. Roy, Jamie Hicks, Petra Vasko, Andreas Heilmann, Anne‐Marie Baston, José M. Goicoechea, Simon Aldridge
Abstract
Abstract Synthetic routes to lithium, magnesium, and zinc aluminyl complexes are reported, allowing for the first structural characterization of an unsupported lithium–aluminium bond. Crystallographic and quantum‐chemical studies are consistent with the presence of a highly polar Li−Al interaction, characterized by a low bond order and relatively little charge transfer from Al to Li. Comparison with magnesium and zinc aluminyl systems reveals changes to both the M−Al bond and the (NON)Al fragment (where NON=4,5‐bis(2,6‐diisopropylanilido)‐2,7‐di‐tert‐butyl‐9,9‐dimethylxanthene), consistent with a more covalent character, with the latter complex being shown to react with CO 2 via a pathway that implies that the zinc centre acts as the nucleophilic partner.