Versatile Reactivity and Theoretical Evaluation of Mono- and Dinuclear Oxidovanadium(V) Compounds of Aroylazines: Electrogeneration of Mixed-Valence Divanadium(IV,V) Complexes

Abstract

ABSTRACT:The substituted hydrazones H 2 L 1−4 (L 1−4 = dibasic tridentate ONO 2− donor ligands) obtained by the condensation of 2-hydroxy-1-naphthaldehyde and 2-aminobenzoylhydrazine (H 2 hnal-abhz) (H 2 L 1 ) , 2-hydroxy-1-naphthaldehyde and 2-hydroxybenzoylhydrazine (H 2 hnal-hbhz) (H 2 L 2 ), 2-hydroxy-1-acetonaphthone and benzoylhydrazine (H 2 han-bhz) (H 2 L 3 ), or 2-hydroxy-1-acetonaphthone and 2-aminobenzoylhydrazine (H 2 hanabhz) (H 2 L 4 ) are prepared and characterized.

Controlling Nuclearity and Stereochemistry in Vanadyl(V) and Mixed Valent VIV/VV Complexes of Oxido‐Pincer Pyridine‐2,6‐dimethanol Ligands

“…Due to spectrometer limitations we were not able to record the maximum of this band but we can assign this to an intervalence charge transfer (IVCT) band of the mixed valent [OV IV (μ‐O)V V O] · – system in line with further reported V IV (μ‐O)V V complexes , , . E.g., the complex [V 2 O 3 (L) 2 ] containing a ONO 2– Schiff base ligand condensed from anthranilhydrazide and 2‐hydroxy acetophenone shows after electrolytic reduction an absorption band at 675 nm, which was assigned to the ligand field 2 B 2 → 2 E transition and an additional absorption in the NIR at 979 nm, which was assigned to an IVCT transition .…”

“…The EPR parameters for the pydim and pydip derivative are similar to those of related mononuclear O=V IV complexes, , , and comparable dinuclear compounds with class I valence‐isolated [OV IV (μ‐O)V V O] units , , , , . Similar valence delocalized (class II or III) behavior as found for [V 2 O 3 (pyphen) 2 ] · – has been previously reported for the radical anionic complexes [(L)OV IV (µ‐O)V V O(LO] · – with tridentate ONO 2– ligands based on hydroxy phenoxy hydrazides,, , , salenes, carboxy‐salicylaldiminates, or azophenolates,, and also the [OV IV (μ‐O oxido )(μ‐O phen )V V O] · 2+ complexes containing pentadentate (N′NONN′) 3– 2,6‐bis(phenoxymethyl‐ N , N ‐dimethylaminomethyl)aminomethyl)‐phenolates,, or complexes [(L)OV IV (µ‐O)V V O(LO] · 3+ complexes containing neutral N′NN′ ligands of the 2,6‐bis[benzimidazol‐2′‐yl]pyridine or ‐amine type, tris(2‐pyridylmethyl)amine, or 1,4,7‐triazacyclononane derivatives …”

Mixed‐Valence Vanadium (IV/V) Glycolates and Lactates with N‐Heterocycle Ligands: Localized Structures and Catalytic Oxidation of Thioanisole

“…This is essentially similar to the reported speciation through stoichiometric mixing of preformed vanadium(V) and ‐(IV) precursor compounds. [10g], [11c] Electrochemical reduction of dinuclear isovalent species[11a], are also reported for the formation of the mixed‐valence divanadium(IV,V) compounds. On the other hand, the amount of heterocyclic ligands should not be excess and the aqueous ethanol solution is helpful for the solubilizing phen and bpy.…”

“…The dimeric units present the largest class, such as [V 2 IV O 2 ] 4+ , [V 2 V O 4 ] 2+ ,[3a] [V 2 IV O 3 ] 2+ , [V 2 V O 3 ] 4+ , and [V 2 IV/V O 3 ] 3+ ,[3b], where the last one with mixed‐valence core has favorable thermodynamic stability and show interesting electronic structures and redox properties. [10b], [10e], …”

“…These complexes were applied for the selective oxidation of thioanisole to methyl phenyl sulfoxide. The chemistry of mixed‐valence vanadium may provide an understanding of the role of the ligand environment in [V 2 IV/V O 3 ] 3+ structures[11a], and the potential use of mixed‐valence systems in catalysis …”