Formation of borane adducts and some complexes starting from N-heterocyclic carbenes
The conjugated mesomeric betaines 2-(1-phenyl-4H-1,2,4-triazolium-4-yl)phenolates and 2-(imidazolium-1-yl)phenolates are in equilibrium with the corresponding N-heterocyclic carbenes (NHCs) which can be trapped as thiones (X-ray analysis). Both (triphenylphosphine)gold(I) chloride and bis(triphenylphosphine)palladium(II) dichloride in THF trapped their N-heterocyclic carbene tautomers 1-(2-phenol)imidazol-2-ylidene as gold and palladium complexes (X-ray analysis). Moreover, the anionic N-heterocyclic carbenes 1-(2-phenolate)triazol-2-ylidene and 1-(2-phenolate)imidazol-2-ylidene can be trapped by triethylborane or triphenylborane to form new zwitterionic heterocyclic ring systems (X-ray analysis). Furthermore, the anionic carbene 1-(2-phenolate)imidazol-2-ylidene gives rhodium and nickel complexes, respectively (X-ray analysis).