Oxidovanadium(iv) and dioxidovanadium(v) complexes of hydrazones of 2-benzoylpyridine and their catalytic applications

Abstract

Reactions between the tridentate ONN donor ligands, Hbzpy-tch () and Hbzpy-inh (), with [V(IV)O(acac)2] in dry methanol give two different types of complexes, [V(IV)O(acac)(bzpy-tch)] () and [V(IV)O(OMe)(bzpy-inh)] (), respectively. Irrespective of their nature in methanol upon aerial oxidation and precipitation both yield dinuclear [{V(V)O(bzpy-tch)}2(μ-O)2] () and [{V(V)O(bzpy-inh)}2(μ-O)2] (). Treatment of or in methanol with H2O2 yields the oxidomonoperoxidovanadium(v) complexes [{V(V)O(bzpy-tch)}2(μ-O2)2] () and [V(V)O(O2)(bzpy-inh)] (). Reactions of and with imidazolomethylpolystyrene cross-linked with 5% divinylbenzene (PS-im) in DMF give the polymer-supported PS-im[V(V)O2(bzpy-inh)] () and PS-im[V(V)O2(bzpy-tch)] (). The compounds are characterized by various spectroscopic techniques and compounds and were also analyzed by thermal, atomic force microscopy (AFM), field-emission scanning electron micrographs (FE-SEM) as well as energy dispersive X-ray (EDAX) studies. The molecular structures of and of [V(V)O(O2)(bzpy-inh)(H2O)]·0.5MeOH () were determined by single-crystal X-ray diffraction, confirming the μ-bis(O) and ONN binding mode in the dinuclear complexes and , as well as the side-on coordination of the peroxido ligand in and . The polymer-grafted compounds and were used for the catalytic oxidation of isoeugenol using aqueous H2O2 as an oxidant. The intermediate peroxido species, expected to be involved during catalytic action, were also generated from solutions of and studied by UV-Vis and (51)V NMR. The catalytic activity of the several systems was tested and the polymer-supported versions showed higher conversions than their neat counterparts. The polymer-supported complexes allow for recyclable catalytic systems, thus providing additional advantages over their homogeneous counterparts in terms of increased catalyst lifetime and easier separation from the reaction mixture.

Di-µ-oxidovanadium(V) Complex with N'-[(Z)-Phenyl(pyridin-2-yl)methylidene]pyridine-4-carbohydrazide: Synthesis, Structural Characterization and in vitro Antidiabetic Inhibition Study

“…= 302.33 g mol for HL. This bands shift toward lower wave numbers on complexation, indicating complexation of azomethine nitrogen to the vanadium [14]. The IR spectra of ligand show a sharp band about 1675 cm -1 due to ν(C=O) of the hydrazide moiety.…”

“…It was prepared following the procedure previously reported [14]. A solution of benzoylhydrazine (0.681 g, 5 mmol) and 2-benzoylpyridine (0.916 g, 5 mmol) were refluxed for 6 h in 25 mL ethanol and cooled to room temperature.…”

“…75.62 (7) V(1)-O(2)-V(1)#1 101.62(9) Symmetry transformations used to generate equivalent atoms: #1 -x,-y+1,-z+1 [14,25]. Oxygen atom of V=O and bridging oxygen atom are responsible for a hydrogen bond interactions.…”

Synthesis and characterization of di-μ-oxidovanadium(V), oxidoperoxido-vanadium(V) and polymer supported dioxidovanadium(V) complexes and catalytic oxidation of isoeugenol

“…Homogeneous and heterogeneous (supported) vanadium complexes have recently been used as catalysts in the oxidation reactions of industrial importance in the presence of a suitable oxidant such as oxidation, oxidative halogenation of organic substrates, oxygen transfer reactions [12,13]. In search of green catalysts for the oxidation of isoeugenol, we have recently designed heterogeneous vanadium complexes based catalysts by immobilizing trigonal bipyrimidal dioxidovanadium(V) complexes through covalent bonding with nitrogen of the imidazole functionalized chloromethylated polystyrene, cross-linked with 5 % divinylbenzene [14]. These catalysts are recyclable and thermally as well as chemically stable.…”

“…Continuing our efforts to immobilizing vanadium complexes and using them as catalysts [12, [14][15][16][17][18], we describe herein the synthesis of dioxidovanadium(V) complex of ONN donor ligand Hbzpy-fah (I) derived from 2-benzoylpyridine and 2-furoylhydrazide (Scheme 1) and its immobilization on polymer-support. This has been achieved via covalent bonding with polymer as shown in Scheme 2.…”