“…Subsequent work has shown versatile coordination behaviour in other indazole-carboxylic acid isomers, although still more commonly coordinating in their monoanionic (N-H) forms. 43 Introducing additional heterocyclic functionality on the fused six-membered ring gives access to a family of ligands not only with lower pK a , and thus with more tendency towards in-situ deprotonation, but also with more compact and geometrically controlled coordination geometries. We recently reported the coordination chemistry of the isomeric pair of ligands pyrazolo[4,3-b]pyridine (4-azaindazole) and pyrazolo[3,4c]pyridine (6-azaindazole), HL6 and HL7 respectively.…”