Wydział Chemii

Abdallah G. Mahmoud

M. Fátima C. Guedes da Silva

Ewelina I. Śliwa

Piotr Smoleński

Maxim L. Kuznetsov

Armando J. L. Pombeiro

2018

Chemistry-An Asian Journal

13

2868-2880

10.1002/asia.201800799

Naukowa

Angielski

Artykuł

The reaction of 3,7‐diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane (DAPTA) with metal salts of Cu^II or Na^I/Ni^II under mild conditions led to the oxidized phosphane derivative 3,7‐diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane‐5‐oxide (DAPTA=O) and to the first examples of metal complexes based on the DAPTA=O ligand, that is, [Cu^II(μ‐CH₃COO)₂(κO‐DAPTA=O)]₂ (1) and [Na(1κOO′;2κO‐DAPTA=O)(MeOH)]₂(BPh₄)₂ (2). The catalytic activity of 1 was tested in the Henry reaction and for the aerobic 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (TEMPO)‐mediated oxidation of benzyl alcohol. Compound 1was also evaluated as a model system for the catechol oxidase enzyme by using 3,5‐di‐tert‐butylcatechol as the substrate. The kinetic data fitted the Michaelis–Menten equation and enabled the obtainment of a rate constant for the catalytic reaction; this rate constant is among the highest obtained for this substrate with the use of dinuclear Cu^IIcomplexes. DFT calculations discarded a bridging mode binding type of the substrate and suggested a mixed‐valence Cu^II/Cu^I complex intermediate, in which the spin electron density is mostly concentrated at one of the Cu atoms and at the organic ligand.

copper, enzymes, homogeneous catalysis, oxidation, phosphane ligands

http://dx.doi.org/10.1002/asia.201800799

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