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

Abstract

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^MesH) 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 ¹⁷O NMR spectroscopy.