Oxygen insertion reactions of mixed N-heterocyclic carbene-oxazolinylborato zinc alkyl complexes.

We report the synthesis of a new mixed oxazoline-carbene scorpionate ligand, bis(4,4-dimethyl-2-oxazolinyl)(1-mesitylimidazolyl)phenylborate (PhB(Ox(Me2))2Im(Mes)). Reactions of the protonated form PhB(Ox(Me2))2(Im(Mes)H) with dialkylzinc compounds provide four-coordinate zinc alkyl complexes, and X-ray diffraction studies of the {PhB(Ox(Me2))2Im(Mes)}ZnR (R = Me, Et) compounds show significant structural distortions involving the R groups shifting away from the carbene donor. The reaction of {PhB(Ox(Me2))2Im(Mes)}ZnEt (3) and O2 provides an isolable mononuclear zinc alkylperoxide {PhB(Ox(Me2))2Im(Mes)}ZnOOEt (4), which has been characterized by single crystal X-ray diffraction and (17)O NMR spectroscopy.