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(TtztBu,Me) ligand. TtztBu,Me formed a four-coordinate (TtztBu,Me)CoCl complex and five-coordinate
(TtztBu,Me)CoNO3 and (TtztBu,Me)ZnOAc complexes. When these
complexes were compared to their TptBu,Me analogues, it was found
that TtztBu,Me resulted in negligible steric differences. K(TtztBu,Me) is
more water-soluble than K(TptBu,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.