Please use this identifier to cite or link to this item: http://ktisis.cut.ac.cy/handle/10488/9964
Title: Structural and electron paramagnetic resonance (EPR) characterization of novel vanadium(V/IV) complexes with hydroquinonate-iminodiacetate ligands exhibiting "noninnocent" activity
Authors: Drouza, Chryssoula 
Stylianou, Marios 
Papaphilippou, Petri Ch 
Keramidas, Anastasios D. 
Keywords: Electron paramagnetic resonance (EPR)
X-ray structure
Hydroquinone
Iminodiacetic
Oxovanadium compounds
Synthesis
Issue Date: 6-Feb-2013
Publisher: IUPAC
Abstract: Reaction of KVO3 with 2-[N,N′-(carboxymethyl)aminomethyl]-5-methylhydroquinone (H4mecah) in aqueous solution at pH 8.2 results in the isolation of mononuclear K2[VV(O)2{Hmecah(-3)}]·2H2O complex. On the other hand, reaction with the 2-[N,N′-(carboxymethyl)aminomethyl]-5-tert-butylhydroquinone (H4tbutcah) under the same conditions gives the tetranuclear mixed-valent complex K 6 [{V V O(μ-O)V IV O}{μ-tbutbicah(-6)}] 2·10.5H2O (H6tbutbicah, 2,2′-({2-[bis(carboxymethyl)amino]-3,6-dihydroxy-4-methylbenzyl}azanediyl)diacetic acid). The structures of both complexes were determined by single-crystal X-ray crystallography. The coordination environment of vanadium ions in both complexes is octahedral, with four out of the six positions to be occupied by the two cis carboxylate oxygens, one hydroquinonate oxygen, and one amine nitrogen atoms of the ligands' tripod binding sites. The importance of the chelate ring strains in the stabilization of the p-semiquinone radical is also discussed. A protonation of the ligated to vanadium(IV) ion hydroquinonate oxygen at low pH was revealed by continuous wave (cw) X-band electron paramagnetic resonance (EPR) and UV-vis spectroscopies.
URI: http://ktisis.cut.ac.cy/handle/10488/9964
ISSN: 00334545
Rights: © 2012 IUPAC.
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