Oxidoperoxidotungsten(VI) and dioxidotungsten(VI) complexes catalyzed oxidative bromination of thymol in presence of H2O2–KBr–HClO4

Maurya, Mannar R.; Rana, Lata; Avecilla, Fernando

doi:10.1016/j.ica.2015.10.045

Cited by 25 publications

(8 citation statements)

References 39 publications

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“…The catalytic potential of the complexes studied here are equally good or slightly better than [V V O 2 ], [30–34] and [Mo VI O 2 ], [35,36] and comparable to [W VI O 2 ] complexes of tridentate ONO donor Schiff base ligands derived from 2‐hydroxyacetophenone and nicotinoylhydrazide and benzoylhydrazide, [11] but selectivity of products slightly differs. The higher amounts of KBr, H 2 O 2 and HClO 4 (2 equivalents each for 10 mmol of substrate) versus lower amounts of these reagents for vanadium and molybdenum complexes might be responsible for such differences.…”

Section: Resultsmentioning

confidence: 64%

“…Selected IR bands are presented in the experimental section. The presence of two characteristics IR bands at 886–901 and 922–942 cm −1 due to the υ sym (O=W=O) and υ asym (O=W=O) stretches, respectively, approves the cis ‐[WO 2 ] core in these complexes [7,9,11,13] . All ligands display a broad band around 3200 cm −1 due to υ(OH) of the phenol and absence of this band in complexes suggests the coordination of phenolate O after deprotonation.…”

Section: Resultsmentioning

confidence: 88%

“…Leaving the chemistry associated with these enzymes, tungsten(VI) complexes having cis ‐[WO 2 ] moiety have mostly been explored for the catalytic epoxidation of alkenes [4–10] . In spite of the good catalytic potentials of these complexes, the growth of the tungsten chemistry, particularly having cis ‐[WO 2 ] moiety is limited [4–13] . After the first report on dioxidotungsten(VI) complexes of hydrogenated analogue of H 2 salen [N,N’‐ethylenebis(salicylideneimine)] (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Biomimetic Oxidative Bromination by cis‐Dioxidotungsten(VI) Complexes of Salan Type N,N’‐Capped Linear Tetradentate Amino Bisphenol

Maurya

Kumar

et al. 2021

Eur J Inorg Chem

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Reaction of [WVIO2(acac)2] (Hacac=acetylacetone) with salan‐type dibasic tetradentate ONNO donor Mannich bases derived from ethylenediamine, formaldehyde and 2,4‐di‐tert‐butylphenol (H2L1), 2‐tert‐butyl‐4‐methylphenol (H2L2), 2,4‐dimethylphenol (H2L3) and 2,4‐dichlorophenol (H2L4) in a 1 : 1 ([WVIO2(acac)2] : H2L) molar ratio in refluxing MeOH gave the corresponding cis‐dioxidotungsten(VI) complexes [WVIO2L1] (1), [WVIO2L2] (2), [WVIO2L3] (3) and [WVIO2L4] (4), respectively. Characterization by elemental analysis, various spectroscopic (FT‐IR, UV‐vis, 1H and 13C NMR) studies, DFT calculations and single‐crystal X‐ray analysis of 2 and 3 suggest six‐coordinated octahedral α‐cis (symmetric) isomeric form of the complexes where ligands coordinate through the two phenolate oxygen and two amine nitrogen atoms (in a cis‐α type symmetric binding mode) with one of the N atoms of the ligand and one of the terminal O atoms of the cis‐WO2 group in the axial position. These complexes are potential catalyst precursors for the oxidative bromination of thymol and styrene. Thymol upon bromination gave three products, namely, 2‐bromothymol, 4‐bromothymol, and 2,4‐dibromothymol; later one being the major product. Oxidative bromination of styrene resulted in 2‐bromo‐1‐phenylethanol and 1‐phenylethane‐1,2‐diol; the later one is the result of nucleophilic attack of water on the α as well as β carbons both of the initially formed 1,2‐dibromo‐1‐phenylethane.

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Section: Resultsmentioning

confidence: 64%

Section: Resultsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Biomimetic Oxidative Bromination by cis‐Dioxidotungsten(VI) Complexes of Salan Type N,N’‐Capped Linear Tetradentate Amino Bisphenol

Maurya

Kumar

et al. 2021

Eur J Inorg Chem

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“…Much of the research effort in catalysis using Earth-abundant metals has focused on 3d metals; however, not all heavy transition metals are precious. Those of the early 4d and 5d series are “green” in both an economic and ecological sense, Figure . − Additionally, in the activation of light alkanes, the generally stronger metal–C and metal–H bond strengths for 4d and 5d metal complexes versus their 3d congeners can mitigate the thermodynamic, and hence kinetic, impediments to nonradical methane activation that often arise due to weak M 3d –C/H bonds …”

Section: Introductionmentioning

confidence: 99%

Tungsten–Ligand Bond Strengths for 2p Elements Including σ- and π-Bond Strength Components, A Density Functional Theory and ab Initio Study

2019

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Three W VI crystal structures with multifarious metal−ligand bond types are used to theoretically predict homolytic metal−element bond enthalpies with 11 popular DFT functionals, MP2 wave function methods, and four common valence basis set/pseudopotentials in order to evaluate the accuracy and precision of the resultant bond enthalpy data. To our knowledge, for the first time, estimates of component metal−ligand σand π-bond strengths are computed. The WE (E = C, N, O) bond enthalpies have the consistent trend σ > second π > first π. In contrast, the element−element BDE trend for the 2p homologues is second π > first π > σ for nitrogen and oxygen, and σ > first π > second π for carbon. These differences may underpin the differences in stability trends and thus reactivity behavior for metal−element multiple bonds as compared to the element−element multiple bonds, and metal−element triple bonds versus their corresponding double bonded counterparts. For example, Odom et al.show that MeI nucleophilically attacks at the imide (MN) rather than the nitride (M ≡ N) ligand; the relative π-bond strengths derived herein provide a thermodynamic rationalization for this site preference. In this study, it is deduced from the calculated thermodynamics that the W−oxo ligand is more congruous with a triple bond than a double bond, consistent with the bonding model set forth in the seminal 1961 Ballhausen− Gray paper.

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“…Although vanadium catalysts show promising activity, their industrial applications are problematic as vanadium compounds are classified as critical according to a European Union regulation and have difficulties to fulfill the criteria of registration, evaluation, authorization, and restriction of chemicals (REACH) . Hetero‐polyoxometallates containing Mo(VI), W(VI), Mn(II‐VII), Cu(II), Ru(III), Ce(IV), Fe(III), Pd(II), Ti(II,IV), and Nb(V) are useful, but often more expensive and less active alternatives . Main group compounds of B(III), Ba(II), Bi(III), Sb(V), Se, and Te have haloperoxidase‐like activity during the synthesis of (hetero) aryl halides, vinyl halides, and alkyl halides by C–H activation …”

Section: Homogeneous Biomimetic Hpo/hg‐like Catalystsmentioning

confidence: 99%

Functional Enzyme Mimics for Oxidative Halogenation Reactions that Combat Biofilm Formation

et al. 2018

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Transition-metal oxide nanoparticles and molecular coordination compounds are highlighted as functional mimics of halogenating enzymes. These enzymes are involved in halometabolite biosynthesis. Their activity is based upon the formation of hypohalous acids from halides and hydrogen peroxide or oxygen, which form bioactive secondary metabolites of microbial origin with strong antibacterial and antifungal activities in follow-up reactions. Therefore, enzyme mimics and halogenating enzymes may be valuable tools to combat biofilm formation. Here, halogenating enzyme models are briefly described, enzyme mimics are classified according to their catalytic functions, and current knowledge about the settlement chemistry and adhesion of fouling organisms is summarized. Enzyme mimics with the highest potential are showcased. They may find application in antifouling coatings, indoor and outdoor paints, polymer membranes for water desalination, or in aquacultures, but also on surfaces for food packaging, door handles, hand rails, push buttons, keyboards, and other elements made of plastic where biofilms are present. The use of natural compounds, formed in situ with nontoxic and abundant metal oxide enzyme mimics, represents a novel and efficient "green" strategy to emulate and utilize a natural defense system for preventing bacterial colonization and biofilm growth.

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Oxidoperoxidotungsten(VI) and dioxidotungsten(VI) complexes catalyzed oxidative bromination of thymol in presence of H2O2–KBr–HClO4

Cited by 25 publications

References 39 publications

Biomimetic Oxidative Bromination by cis‐Dioxidotungsten(VI) Complexes of Salan Type N,N’‐Capped Linear Tetradentate Amino Bisphenol

Biomimetic Oxidative Bromination by cis‐Dioxidotungsten(VI) Complexes of Salan Type N,N’‐Capped Linear Tetradentate Amino Bisphenol

Tungsten–Ligand Bond Strengths for 2p Elements Including σ- and π-Bond Strength Components, A Density Functional Theory and ab Initio Study

Functional Enzyme Mimics for Oxidative Halogenation Reactions that Combat Biofilm Formation

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