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Title: Vanadium(IV and v) complexes of pyrazolone based ligands: Synthesis, structural characterization and catalytic applications
Authors: Maurya, Mannar Ram
Sarkar B.
Avecilla F.
Correia I.
Published in: Dalton Transactions
Abstract: The ONO donor ligands obtained from the condensation of 4-benzoyl-3-methyl-1-phenyl-2-pyrazoline-5-one (Hbp) with benzoylhydrazide (H2bp-bhz I), furoylhydrazide (H2bp-fah II), nicotinoylhydrazide (H2bp-nah III) and isonicotinoylhydrazide (H2bp-inh IV), upon treatment with [VIVO(acac)2], lead to the formation of [VIVO(bp-bhz)(H2O)] 1, [VIVO(bp-fah)(H2O)] 2, [VIVO(bp-nah)(H2O)] 3 and [VIVO(bp-inh)(H2O)] 4, respectively. At neutral pH the in situ generated aqueous K[H2VVO4] reacts with ligands I and II, forming potassium salts, K(H2O)2[VVO2(bp-bhz)] 5 and K(H2O)2[VVO2(bp-fah)] 6, while ligands III and IV give neutral complexes, [VVO2(Hbp-nah)] 9 and [VVO2(Hbp-inh)] 10, respectively. Acidification of aqueous solutions of 5 and 6 with HCl also gives neutral complexes [VVO2(Hbp-bhz)] 7 and [VVO2(Hbp-fah)] 8, respectively. Complexes 1-4, upon slow aerial oxidation in methanol, convert into monooxidovanadium(v) complexes, [VVO(bp-bhz)(OMe)] 11, [VVO(bp-fah)(OMe)] 12, [VVO(bp-nah)(OMe)] 13 and [VVO(bp-inh)(OMe)] 14, respectively. All complexes were characterized by various spectroscopic techniques like FT-IR, UV-visible, EPR (for complexes 1-4) and NMR (1H, 13C and 51V), elemental analysis, thermogravimetry and single crystal X-ray diffraction (for complexes 5-10 and 12). In the solid state, all complexes characterized by X-ray diffraction show the metal ion 5-coordinated in a distorted square pyramidal geometry. Complexes 11-14 were tested as catalysts for the one-pot three-component (ethylacetoacetate, benzaldehyde and ammonium acetate) dynamic covalent assembly, via Hantzsch reaction, using hydrogen peroxide as oxidant in solution and under solvent-free conditions. The complexes are also active catalysts for the oxidation of tetralin to tetralone with H2O2 as oxidant. The influence of the amounts of catalyst and oxidant, and solvent, temperature and time on the catalyzed reactions was investigated. © 2016 The Royal Society of Chemistry.
Citation: Dalton Transactions, 45(43): 17343-17364
Issue Date: 2016
Publisher: Royal Society of Chemistry
Keywords: Catalysts
Electron spin resonance spectroscopy
Metal ions
Single crystals
Spectroscopic analysis
Thermogravimetric analysis
Vanadium compounds
X ray diffraction
Catalytic applications
Catalyzed reactions
Covalent assemblies
Single crystal x-ray diffraction
Solvent free conditions
Spectroscopic technique
Square-pyramidal geometry
Structural characterization
Synthesis (chemical)
ISSN: 14779226
Author Scopus IDs: 7005255411
Author Affiliations: Maurya, M.R., Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, India
Sarkar, B., Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, India
Avecilla, F., Departamento de Química Fundamental, Universidade da Coruña, Campus de A Zapateira, A Coruña, 15071, Spain
Correia, I., Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, Lisboa, 1049-001, Portugal
Funding Details: MRM thanks the Science and Engineering Research Board (SERB), Government of India, New Delhi for financial support of this work (EMR/2014/000529). BS is thankful to IIT Roorkee for awarding a MHRD fellowship. I. Correia acknowledges Funda??o para a Ci?ncia e Tecnologia for an Investigator FCT contract, UID/QUI/00100/2013, and the IST-UTL Centers of the Portuguese NMR. Science and Engineering Research Board, SERB: EMR/2014/000529; Fundação para a Ciência e a Tecnologia, FCT: UID/QUI/00100/2013; Ministry of Human Resource Development, MHRD
Corresponding Author: Maurya, M.R.; Department of Chemistry, India; email:
Appears in Collections:Journal Publications [CY]

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