Valence Delocalization in a Mixed-Oxidation Divanadium (IV, V) Complex Electrogenerated from Its Structurally Characterized Divanadium (V) Analogue with a Tridentate (ONO) Ligand

Abstract

A new complex containing the {OVv(μ-O)VvO}4+ unit has been synthesized and structurally characterized. Cyclic voltammogram of this complex showed that the two VV centers of the V2O3 4+ core are found to undergo electrochemical reduction in two distinctly separate steps not observed previously in similar systems. A rare mixed-oxidation state species [L(O)VIVOVV(O)L]- has been electrogenerated from the structurally characterized parent divanadium (V) species in solution state and characterized by IR, EPR, and electronic spectroscopy.

Synthesis and characterization of bis-acylhydrazone derivatives as tetradentate ligands and their dinuclear metal(II) complexes

“…The tautomeric keto forms of ligands were also indicated by 1 H-NMR spectroscopy since the enolic OH signals of enol forms of ligands were not observed but amide NH signal of keto forms appeared around 10.14-11.19 ppm [17,18]. Furthermore, the observation of strong ν(C=O) absorption bands around 1649-1664 cm −1 in the infrared spectra of the ligands suggest that the ligands are in the keto form in the solid state [19,20] In the case of (H 2 L 1 ) ligand a broad peak is observed in the 3322 cm −1 region which is assigned to phenolic (OH) absorption, while in the case of IR spectra of (H 2 L 2 ) ligand, the peaks observed at 1521 and 1353 cm −1 are attributed to symmetric and asymmetric stretching vibrations of nitro group [17,20], [28]- [31]. The characteristic IR peaks of hydrazone compounds synthesized in this work are given in Table 3.…”

“…probably due to (C=N-N=C) and (C-O) stretching, respectively, suggesting that the NH proton is likely lost via deprotonation induced by the metal and the resulting enolic oxygen and the azomethine nitrogen take place in coordination [19][20][21]. The shift of ν(N-N) stretch of the complexes to higher energy by ∼15-31 cm −1 comparing to that of free ligand can be another evidence for the involvement of azomethine nitrogen in coordination [28,31,32].…”

Synthesis, X-ray structure and DFT calculation of oxido-vanadium(V) complex with a tridentate Schiff base ligand

“…p* transition [24]. The lowest energy transition band is observed near 441 nm, which is attributed to a LMCT charge transfer from a p-orbital on the lone-pair of the ligand oxygen atoms to the empty d-orbital of the vanadium atom [25].…”

A Study of Anti-inflammatory and Analgesic Activity of New 2,3-Disubstituted 1,2-Dihydroquinazolin-4(3H)-one Derivative and Its Transition Metal Complexes

“…All the solvents were distilled before use. o-Aminobenzoylhydrazide 27) and o-hydroxyacetophenone-o-aminobenzoylhydrazone 28) were prepared following the literature procedures.Physical Measurements Metal content of the complexes was determined after wet ashing with HCl and HClO 4 by gravimetric methods for Karnataka-587101, India. Received September 20, 2009; accepted February 11, 2010; …”