TY - JOUR

T1 - Novel Copper(II) Complexes with BIAN Ligands: Synthesis, Structure and Catalytic Properties of the Oxidation of Isopropylbenzene

AU - Fomenko, Iakov S.

AU - Koshcheeva, Olga S.

AU - Kuznetsova, Nina I.

AU - Larina, Tatyana V.

AU - Gongola, Marko I.

AU - Afewerki, Medhanie

AU - Abramov, Pavel A.

AU - Novikov, Alexander S.

AU - Gushchin, Artem L.

PY - 2023/5/8

Y1 - 2023/5/8

N2 - Two new isomeric complexes [CuBr2(R-bian)] (R = 4-Me-Ph (1), 2-Me-Ph (2)) were obtained by reacting copper(II) bromide with 1,2-bis[(2-methylphenyl)imino]acenaphthene ligands and characterized. The crystal structure of 2 was determined by X-ray diffraction analysis. The copper atom has a distorted square-planar environment; the ω angle between the CuN2 and CuBr2 planes is 37.004°. The calculated ω parameters for optimized structures 1 and 2 were 76.002° and 43.949°, indicating significant deviations from the ideal tetrahedral and square-plane geometries, respectively. Molecules 2 form dimers due to non-covalent Cu···Br contacts, which were analyzed by DFT calculations. The complexes were also characterized by cyclic voltammetry and UV-Vis spectroscopy. A quasi-reversible Cu(II)/Cu(I) redox event with E1/2 potentials of 0.81 and 0.66 V (vs. SHE) was found for 1 and 2, respectively. The electronic absorption spectra showed the presence of Cu(I) species as a result of the partial reduction of the complexes in the acetonitrile solution. Both complexes were tested as homogenous catalysts for the oxidation of isopropylbenzene (IPB) in acetonitrile at low temperatures. Differences in the mechanism of the catalytic reaction and the composition of the reaction products depending on the oxidizing ability of the catalyst were revealed.

AB - Two new isomeric complexes [CuBr2(R-bian)] (R = 4-Me-Ph (1), 2-Me-Ph (2)) were obtained by reacting copper(II) bromide with 1,2-bis[(2-methylphenyl)imino]acenaphthene ligands and characterized. The crystal structure of 2 was determined by X-ray diffraction analysis. The copper atom has a distorted square-planar environment; the ω angle between the CuN2 and CuBr2 planes is 37.004°. The calculated ω parameters for optimized structures 1 and 2 were 76.002° and 43.949°, indicating significant deviations from the ideal tetrahedral and square-plane geometries, respectively. Molecules 2 form dimers due to non-covalent Cu···Br contacts, which were analyzed by DFT calculations. The complexes were also characterized by cyclic voltammetry and UV-Vis spectroscopy. A quasi-reversible Cu(II)/Cu(I) redox event with E1/2 potentials of 0.81 and 0.66 V (vs. SHE) was found for 1 and 2, respectively. The electronic absorption spectra showed the presence of Cu(I) species as a result of the partial reduction of the complexes in the acetonitrile solution. Both complexes were tested as homogenous catalysts for the oxidation of isopropylbenzene (IPB) in acetonitrile at low temperatures. Differences in the mechanism of the catalytic reaction and the composition of the reaction products depending on the oxidizing ability of the catalyst were revealed.

KW - copper complexes

KW - BIAN ligands

KW - redox-active ligands

KW - oxidation

KW - isopropylbenzene

UR - https://www.mendeley.com/catalogue/732f9e39-583d-31a4-bb3a-fdf31578e0f2/

U2 - 10.3390/catal13050849

DO - 10.3390/catal13050849

M3 - Article

VL - 13

JO - Catalysts

JF - Catalysts

SN - 2073-4344

IS - 5

M1 - 849

ER -