SymmetricalBis-Hydrazone Ligand-Based Binuclear Oxido/Dioxido-Vanadium(IV/V)Complexes: Synthesis, Reactivity, and Catalytic Applications for theSynthesis of Biologically Potent 2‑Phenylquinazolin-4-(3<i>H</i>)‑ones
Symmetrical bis(hydrazone)-based ligands, H<sub>4</sub>dar(bhz)<sub>2</sub> (<b>I</b>), H<sub>4</sub>dar(fah)<sub>2</sub> (<b>II</b>), H<sub>4</sub>dar(nah)<sub>2</sub> (<b>III</b>), and H<sub>4</sub>dar(inh)<sub>2</sub> (<b>IV</b>) obtained from 4,6-diacetylresorcinol (H<sub>2</sub>dar) and different hydrazides [benzoylhydrazide (Hbhz), isonicotinoylhydrazide (Hinh), nicotinoylhydrazide (Hnah), and 2-furoylhydrazide (Hfah)], were used to prepare potassium salts of binuclear <i>cis</i>-[V<sup>V</sup>O<sub>2</sub>]<sup>+</sup> complexes, {K(H<sub>2</sub>O)<sub>2</sub>}<sub>2</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>2</sub>dar(bhz)<sub>2</sub>] (<b>1</b>), {K(H<sub>2</sub>O)<sub>2</sub>}<sub>2</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>2</sub>dar(fah)<sub>2</sub>] (<b>2</b>), {K(H<sub>2</sub>O)<sub>2</sub>}<sub>2</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>2</sub>dar(nah)<sub>2</sub>] (<b>3</b>), and {K(H<sub>2</sub>O)<sub>2</sub>}<sub>2</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>2</sub>dar(inh)<sub>2</sub>] (<b>4</b>), and binuclear [V<sup>IV</sup>O]<sup>2+</sup> complexes, [{V<sup>IV</sup>O(MeOH)}<sub>2</sub>dar(bhz)<sub>2</sub>] (<b>5</b>), [{V<sup>IV</sup>O(MeOH)}<sub>2</sub>dar(fah)<sub>2</sub>] (<b>6</b>), [{V<sup>IV</sup>O(MeOH)}<sub>2</sub>dar(nah)<sub>2</sub>] (<b>7</b>), and [{V<sup>IV</sup>O(MeOH)}<sub>2</sub>dar(inh)<sub>2</sub>] (<b>8</b>). In the presence of warm MeOH/DMSO (4:1), <b>3</b> changed to {K(H<sub>2</sub>O)<sub>2</sub>}[(V<sup>V</sup>O<sub>2</sub>)<sub>2</sub>Hdar(nah)<sub>2</sub>]<b>·</b>DMSO (<b>3a</b>·DMSO). Single crystal XRD studies of <b>1</b> and <b>3a</b> confirm a binuclear structure along with a distorted square pyramidal geometry of each vanadium center where bis{ONO(2−)} ligands coordinate through phenolate-O, azomethine-N, and enolate-O atoms of each unit. While growing crystals of <b>6</b> in EtOH, part of it oxidizes and gives [{V<sup>V</sup>O(OEt)}<sub>2</sub>dar(fah)<sub>2</sub>] (<b>9</b>) along with powdery <b>6</b>. Complex <b>9</b> has a distorted octahedral structure. These complexes were used as catalysts for the synthesis of biologically important 2-phenylquinazolin-4-(3<i>H</i>)-ones having different aryl aldehydes, and they all show excellent catalytic performance (up to 97% yield) in less reaction time and low temperature, in the presence of 70% aqueous TBHP/30% aqueous H<sub>2</sub>O<sub>2</sub> as a greener oxidant. Generally, these complexes perform better than their mononuclear analogues. Spectroscopy, DFT studies, and isolated intermediates have helped in proposing a suitable reaction mechanism for the catalytic reaction.
Publication Details
- Journal
- Figshare
- Published
- 2025-01-22
- DOI
- https://doi.org/10.1021/acs.inorgchem.4c04035.s001
- Primary Topic
- Vanadium and Halogenation Chemistry
- Type
- article
- Field-Weighted Citation Impact
- 0.00