Gilles Schnee, David Specklin, J. Djukic
May 17, 2016
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0
Influential Citations
8
Citations
Journal
Organometallics
Abstract
The sterically bulky NHCs 1,3-di-tert-butylimidazol-2-ylidene (ItBu), 1,3-di-tert-butylimidazolin-2-ylidene (StBu), and 1,3-di-tert-butyl-3,4,5,6-tetrahydripyrimidin-2-ylidene (C6-tBu) were found to readily react with excess Al2Me6 at room temperature to form salts 2, 3, and 4, respectively, consisting of the polynuclear Me3Al(μ3-CH2)(AlMe2)2(μ2-CH3)− anion associated with either the cation ItBu-H+, StBu-H+, or C6-tBu-H+. Such a reaction involving the deprotonation of an Al2Me6 moiety by a NHC does not proceed with less sterically hindered NHCs such as 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IDipp) and 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes), for which only the classical Lewis pair adducts (NHC)AlMe3 were isolated. In line with experimental and density functional theory (DFT) calculations data, such reactivity thus appears to be driven by steric frustration, resulting in the destabilization of the corresponding (NHC)AlMe3 adducts, then more prone to dissociate and hence allowing ...