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Copper(II) and Sodium(I) Complexes based on 3,7‐Diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane‐5‐oxide: Synthesis, Characterization, and Catalytic Activity
Author(s) -
Mahmoud Abdallah G.,
Guedes da Silva M. Fátima C.,
Śliwa Ewelina I.,
Smoleński Piotr,
Kuznetsov Maxim L.,
Pombeiro Armando J. L.
Publication year - 2018
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201800799
Subject(s) - chemistry , nonane , catalysis , copper , metal , reaction rate constant , valence (chemistry) , medicinal chemistry , benzyl alcohol , ligand (biochemistry) , substrate (aquarium) , oxide , inorganic chemistry , organic chemistry , kinetics , biochemistry , physics , receptor , oceanography , quantum mechanics , geology
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‐CH 3 COO) 2 (κ O ‐DAPTA=O)] 2 ( 1 ) and [Na(1κ OO′ ;2κ O ‐DAPTA=O)(MeOH)] 2 (BPh 4 ) 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 1 was 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 II complexes. 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.