322
Views
35
CrossRef citations to date
0
Altmetric
Original Articles

Crystal structure, electrochemistry, and catalytic studies of a series of new oxidovanadium(IV) Schiff-base complexes derived from 1,2-diphenyl-1,2-ethylenediamine

, , , &
Pages 840-855 | Received 03 Dec 2011, Accepted 02 Jan 2012, Published online: 21 Feb 2012
 

Abstract

New derivatives of N2O2 tetradentate Schiff bases, from condensation of meso-1,2-diphenyl-1,2-ethylenediamine and salicylaldehyde derivatives (X-salicylaldehyde; X = 3-OMe, 4-OMe, 5-OMe, 6-OMe, 5-Cl, 5-Me), and oxidovanadium(IV) complexes were synthesized and characterized by 1H NMR, UV-Vis, IR spectroscopy, and elemental analysis. Crystal structure of 5-OMe; H2L3 and two of the complexes (VOL2 and VOL3) were also obtained. In the crystals, the molecule of H2L3 is Ci symmetrical, as it occupies the special position on the center of symmetry; its conformation is partially determined by classical intramolecular O–H···N hydrogen bonds. The complexes have monomeric structures with a distorted square pyramid of vanadium, with the oxo ligand in the apical position. Cyclic voltammetry studies show quasi-reversible VIV/VV redox for which the presence of electron-withdrawing groups on salicylaldehyde derivatives shifts the E° to more positive values. The complexes were used as catalysts for selective epoxidation of cyclooctene with tert-butylhydroperoxide as oxidant, in various solvents and reaction conditions. High catalytic activities and excellent selectivity was found. The catalytic activity of the complexes increased increasing E°, a consequence of the presence of electronegative substituents. This epoxidation process with the new catalysts was also studied under solvent-free condition and excellent reactivity was observed.

Acknowledgments

We acknowledge the office of gifted student at the University of Semnan for the financial support.

Reprints and Corporate Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

To request a reprint or corporate permissions for this article, please click on the relevant link below:

Academic Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

Obtain permissions instantly via Rightslink by clicking on the button below:

If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.