A new bis-phenolate mesoionic carbene ligand for early transition metal chemistry

We report the synthesis of a new pincer-type triazolylidene ligand precursor H3L[Cl] with redox-active 3,5-di-tert-butylphenolate substituents on a multigram scale following a converging ten-step route. The potential of this new mesoionic carbene ligand in early transition metal chemistry is explored. This includes the synthesis of the first triazole-derived mesoionic carbene complexes of titanium, niobium and molybdenum as well as the first example of MIC imido complexes of these elements. Furthermore, the reactivity as well as the electrochemical properties of the new complexes are compared to known, comparable bis-phenolate NHC complexes.