3,3'-Methylenebis(1-tert-butyl-3-imidazolium bromide) (
1) and
3,3'-methylenebis[1-(2,6-diisopropylphenyl)-3-imidazolium bromide] (
2) are bidendate
N-heterocyclic carbene (NHC) ligands, which form various transition metal complexes. For example,
1 generates a carbene complex with palladium(II) acetate, and shows catalytic activities in Heck couplings and Suzuki couplings.
1) Similarly, a palladium complex of
2, bearing 2,6-diisopropylphenyl groups on NHC nitrogen atoms, can be applied to Suzuki coupling.
2) Since these ligands can complex with not only palladium but also other transition metals like platinum,
3) rhodium,
4) nickel
5) and chromium,
6) the study of their catalytic activities is expected in the future.