Crystal structure, electrochemistry, and catalytic studies of a series of new oxidovanadium(IV) Schiff-base complexes derived from 1,2-diphenyl-1,2-ethylenediamine
New derivatives of N 2 O 2 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 1 H NMR, UV-Vis, IR...
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| Vydáno v: | Journal of coordination chemistry Ročník 65; číslo 5; s. 840 - 855 |
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| Hlavní autoři: | , , , , |
| Médium: | Journal Article |
| Jazyk: | angličtina |
| Vydáno: |
Abingdon
Taylor & Francis Group
10.03.2012
Taylor & Francis Ltd |
| Témata: | |
| ISSN: | 0095-8972, 1029-0389 |
| On-line přístup: | Získat plný text |
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| Shrnutí: | New derivatives of N
2
O
2
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
1
H NMR, UV-Vis, IR spectroscopy, and elemental analysis. Crystal structure of 5-OMe; H
2
L
3
and two of the complexes (VOL
2
and VOL
3
) were also obtained. In the crystals, the molecule of H
2
L
3
is C
i
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 V
IV
/V
V
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. |
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| Bibliografie: | SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 14 ObjectType-Article-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0095-8972 1029-0389 |
| DOI: | 10.1080/00958972.2012.662275 |