Soft scorpionate ligands based on imidazole-2-thione donors

This review describes the development. of the anionic soft scorpionate ligand hydrotris(methimazolyl)borate (Tm-Mc), its N-alkyl and N-aryl congeners and draws comparisons where appropriate with its close relatives, the dihydrobis(methimazolyl)borates (Bm(R)). Key features of the interaction of these species with metal centres, including bonding modes, electron-donor properties, M center dot center dot center dot H-B interactions, ligand degradation and metallaboratrane formation are addressed and a summary of the coordination chemistry of these species with both main (Foul) and transition metals is given.