Premium
Polynuclear Copper(II) Complexes as Catalysts for the Peroxidative Oxidation of Cyclohexane in a Room‐Temperature Ionic Liquid
Author(s) -
Jlassi Raja,
Ribeiro Ana P. C.,
Guedes da Silva M. Fátima C.,
Mahmudov Kamran T.,
Kopylovich Maximilian N.,
Anisimova Tatiana B.,
Naïli Houcine,
Tiago Gonçalo A. O.,
Pombeiro Armando J. L.
Publication year - 2014
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.201402352
Subject(s) - chemistry , ionic liquid , acetonitrile , catalysis , cyclohexane , tetrafluoroborate , medicinal chemistry , inorganic chemistry , copper , imidazole , nuclear chemistry , organic chemistry
The reaction of copper(II) nitrate hydrate with sodium 2‐[2‐(2,4‐dioxopentan‐3‐ylidene)hydrazinyl]terephthalate (Na 2 H L 1 ) in the absence or presence of imidazole (im) leads to the new complexes [(H 2 O)Cu 0.5 {(μ‐ L 1 ‐1κ O :2κ 3 N , O′ , O″ )Cu(H 2 O) 2 }] 2 ( 1 ) and [Cu(im)(μ‐H L 1 ‐1κ O :2κ 3 N , O , O′ )] 2 ( 2 ), respectively, whereas the 1D coordination polymer [Cu 2 (H 2 O) 2 (μ‐H 2 L 2 ‐1κ 3 N , O , O′ :2κ O″ )(μ‐ L 2 ‐1κ 3 N , O , O′ :2κ 2 N′ , O″ )] n ( 3 ) is obtained from Cu(NO 3 ) 2 · 2.5H 2 O and sodium 2‐[2‐(4,4‐dimethyl‐2,6‐dioxocyclohexylidene)hydrazinyl]terephthalate (Na 2 H L 2 ). All of the compounds were characterized by ESI‐MS, IR spectroscopy, elemental analysis and X‐ray diffraction analysis. Di‐ or tri‐deprotonated ligands display different coordination modes and lead to distinct nuclearities of the Cu II complexes depending on the conditions used for the syntheses. Complexes 1 – 3 were successfully tested as dual‐role catalysts for cyclohexane oxidation under acid‐free conditions in the ionic liquid [1‐butyl‐3‐methylimidazolium tetrafluoroborate, (bmim)(BF 4 )] as well as in acetonitrile. The application of the ionic liquid (IL) increased the product yield and turnover number and decreased the reaction time, in comparison with those for the use of the conventional acetonitrile solvent. Easy recycling of the catalyst, with preservation of almost the initial activity and selectivity, was also achieved by using the IL medium.