Employing Linear Tridentate Ligands with Pyrazole End Groups in Catalytic Tyrosinase Model Chemistry: Does Hemilability Matter?

Several copper(I) and copper(II) complexes supported by hemilabile bis(pyrazolylmethyl)amine (pzma) ligands are synthesized and structurally characterized. The copper(I) complexes with hexafluoridophosphate or perchlorate anions are employed as catalysts for the tyrosinase-like oxygenation of 2,4-di-tert-butylphenol (DTBP-H). Their activities are comparable to that of [Cu(MeCN)(2)PMP]PF6 (PMP= pyrazolylmethylpyridine) investigated earlier. In contrast to the copper(I) pzma complexes, their congeners supported by non-hemilabile bis(pyrazolylethyl)amine (pzea) ligands are found to be catalytically inactive.