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Tyrosinase Model Systems Supported by Pyrazolylmethylpyridine Ligands: Electronic and Steric Factors Influencing the Catalytic Activity and Impact of Complex Equilibria in Solution
Author(s) -
Herzigkeit Benjamin,
Flöser Benedikt M.,
Engesser Tobias A.,
Näther Christian,
Tuczek Felix
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201800319
Subject(s) - homoleptic , chemistry , steric effects , denticity , catalysis , ligand (biochemistry) , reactivity (psychology) , electronic effect , stereochemistry , combinatorial chemistry , pyrazole , pyridine , medicinal chemistry , crystal structure , crystallography , organic chemistry , metal , receptor , medicine , biochemistry , alternative medicine , pathology
Two new copper(I) complexes supported by pyrazolylmethylpyridine ( PMP ) ligands are synthesized and investigated regarding their ability to catalyze the oxygenation of several monophenolic substrates. The PMP ligands containing a pyridine and a pyrazole donor group represent hybrids between dipyridylmethane ( DPM ) and bis(pyrazolyl)methane ( BPM ) ligands. The catalytic activity of the two new [Cu(MeCN) 2 PMP ]PF 6 complexes is found to be intermediate between that of catalytically inactive [Cu(MeCN) 2 DPM ]PF 6 and highly active [Cu(MeCN) 2 BPM ]PF 6 , suggesting that the electronic properties of a multidentate ligand can be designed in a modular fashion. DFT calculations are used to explore the differences in reactivity between the two systems. Regarding the behavior of these complexes in solution, evidence for an equilibrium between homoleptic and heteroleptic forms is presented. The crystal structure of a dinuclear complex exhibiting two homoleptic Cu II units bridged by a fluorido ligand is obtained, which might represent one of the decay products of PMP ‐type catalysts after prolonged reaction times.