Reaction of sterically congested NHC–Zn(CH2CH3)2 with substituted phenols leading to zincate complexes

We report the reaction of a sterically congested NHC–Zn(CH2CH3)2 Lewis adduct (1) prepared through reaction of an equimolar ratio of 1,3-di-tert-butylimidazol-2-ylidene and diethyl zinc, with various substituted phenols (4-tert-butyl-phenol, 2,6-di-tert-butyl-4-methyl phenol, and 1-bromo-4,6-di-tert-butyl phenol). The NHC–Zn dative bond was cleaved in each of the reactions with the substituted phenols to afford the corresponding ionic complexes of imidazolium cation and aryloxo-zincate, [{(4-CMe3C6H4O)2Zn(μ-OC6H4-4-CMe3)}2{(1,3-(CMe3)2-ImCH}2] (2), [{(2,6-(CMe3)2-4-Me-C6H3O)2}Zn{(1,3-(CMe3)2-ImCH}] (3), and [{(1-Br-3,5-(CMe3)2C6H2O)2}2-Zn{(1,3-(CMe3)2-ImCH}] (4), where 1,3-(CMe3)2-ImCH) is imidazolium carbocation. The molecular structures of 1–4 were established by X-ray diffraction analyses and from the solid-state structures of 2–4, it was confirmed that, in all the compounds, zinc ions are coordinated through substituted phenolate groups.