Trinuclear cis-dioxidomolybdenum(VI) complexes of compartmental C symmetric ligands: Synthesis, characterization, DFT study and catalytic application for hydropyridines (Hps) via the Hantzsch reaction

Autor: Reshu Tomar, Puneet Gupta, Mannar R. Maurya, Fernando Avecilla
Rok vydání: 2020
Předmět:
Zdroj: Polyhedron. 186:114617
ISSN: 0277-5387
DOI: 10.1016/j.poly.2020.114617
Popis: Trinuclear cis-dioxidomolybdenum(VI) complexes of the type [{MoVIO2(MeOH)}3L1-7] (1–7) have been synthesized using tris(H2ONO) donor ligands [H6L1-7 (I–VII)] assembled from benzene-1,3,5-tricarbohydrazide (bthz) and the corresponding salicylaldehyde (sal). All the ligands and the complexes were characterized by numerous techniques, such as FT-IR, UV–visible, NMR (1H and 13C) spectroscopy, electrochemical study, elemental analysis, thermogravimetric study and single crystal X-ray diffraction of the ligand III and complexes 1 and 5. In the presence of H2O2 as an oxidant, these complexes show excellent catalytic potential towards the one-pot three-components [ethyl acetoacetate, benzaldehyde (or its derivatives) and ammonium acetate] dynamic covalent assembly in the Hantzsch reaction. Under solvent free conditions, as high as 98% conversion along with 100% selectivity towards diethyl 2,6-dimethyl-4-phenyl-1,4-dihydropyridine-3,5-dicarboxylate (1,4-DHP) has been achieved in 1 h. Although solvents do not improve the conversion, they do influence the selectivity of the products. With the elapse of time, the conversion of dihydropyridine to the diethyl 2,6-dimethyl-4-phenylpyridine-3,5-dicarboxylate derivative occurs and completes in ca. 10 h with a distinct color change, showing the importance of the catalysts. Efforts have been made to provide suitable reaction pathways for the catalytic reaction based on spectroscopic and density functional theory studies.
Databáze: OpenAIRE
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