Sterically Bulky Tris(triazolyl)borate Ligands as Water-Soluble Analogues of Tris(pyrazolyl)borate

The recently synthesized 3-tert-butyl-5-methyl-1,2,4-triazole reacted with KBH4 to give the new potassium tris(3-tert-butyl-5-methyl-1,2,4-triazolyl)borate K(Ttz t Bu,Me) ligand. Ttz t Bu,Me formed a four-coordinate (Ttz t Bu,Me)CoCl complex and five-coordinate (Ttz t Bu,Me)CoNO3 and (Ttz t Bu,Me)ZnOAc complexes. When these complexes were compared to their Tp t Bu,Me analogues, it was found that Ttz t Bu,Me resulted in negligible steric differences. K(Ttz t Bu,Me) is more water-soluble than K(Tp t Bu,Me), so bulky tris(triazolyl)borate ligands should lead to functional models for enzyme active sites in an aqueous environment and the creation of water-soluble analogues of Tp catalysts.