Introduction of bulky tert-butyl substituents on the core of N,N′-diaryl N-heterocyclic carbenes through the corresponding vicinal diamines

Highly bulky N,N′-diaryl imidazolinium salts substituted by one or two tert-butyl groups on the heterocyclic backbone and the corresponding silver N-heterocyclic carbene complexes are obtained by the addition of tert-butyl magnesium chloride or tert-butyl lithium on symmetrical 1,2-bisimines derived from 2,6-diisopropylaniline, 2,6-diethylaniline and 2,4,6-trimethylaniline.