Theoretical and experimental studies on stability, bonding and isolation of elusive bis-(dichloro-aluminium) oxides supported by donor-base ligands.

Herein, we depict the stability, and bonding studies of bis-(dichloro-aluminium) oxides ClAl-O-AlCl supported by a pair of homo-/hetero-leptic donor base ligands L, L' [L, L' = cyclic alkyl(amino) carbene (cAAC; 1); N-heterocyclic carbene (NHC; 2); di-amido carbene (DAC; 3); L = cAAC, L' = NHC; (4)] with a general formula (L)Al(Cl)-O-Al(Cl)(L') (1-4) by NBO, QTAIM and EDA-NOCV analyses. Theoretical calculations suggest that 1-4 possess favorable interaction energies (Δ ), and bond dissociation energies between L/L', and Al(Cl)-O-Al(Cl) fragments the formation of two dative L→Al bonds [1 > 4 > 2 > 3]. This trend is rationalized by the σ-donor ability of the ligands L/L'. Moreover, we depict the first successful solid-state isolation of the colorless compound (cAAC)Al(Cl)-O-Al(Cl)(cAAC) (1') by reacting cAAC and AlCl in the presence of a controlled amount of HO, where two equiv. of cAAC is being utilized as the base. 1' has been structurally characterized by single-crystal X-ray diffraction, and further studied by NMR spectroscopy.