Synthesis, Structure, and Reactivity of a New Mononuclear Molybdenum(<scp>VI</scp>) Complex Resembling the Active Center of Molybdenum Oxotransferases

Dinda, Rupam; Sengupta, Parbati; Ghosh, Saktiprosad; Sheldrick, William S.

doi:10.1002/ejic.200390049

Cited by 126 publications

(79 citation statements)

References 29 publications

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“…5,6,7 In the current contribution, we although similar reactivity with MoO2Cl2 derivatives has been observed earlier. 8,9 In general, the cleavage of both metal-oxo bonds and the formation of a Mo(VI) compound without any multiply bonded terminal ligands is rare.…”

Section: Chart 1)supporting

confidence: 86%

Heptacoordinated Molybdenum(VI) Complexes of Phenylenediamine Bis(phenolate): A Stable Molybdenum Amidophenoxide Radical

et al. 2013

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The syntheses, crystallographic structures, magnetic properties, and theoretical studies of two heptacoordinated molybdenum complexes with N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,2-phenylenediamine (H 4 N 2 O 2 ) are reported. A formally molybdenum(VI) complex [Mo(N 2 O 2 )Cl 2 (dmf)] (1) was synthesized by the reaction between [MoO 2 Cl 2 (dmf) 2 ] and H 4 N 2 O 2 , whereas the other molybdenum(VI) complex [Mo(N 2 O 2 )(HN 2 O 2 )] (2) was formed when [MoO 2 (acac) 2 ] was used as a molybdenum source. Both complexes represent a rare case of the Mo VI ion without any multiply bonded terminal ligands. In addition, molecular structures, magnetic measurements, ESR spectroscopy, and density functional theory calculations indicate that complex 2 is the first stable molybdenum(VI) amidophenoxide radical.

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Section: Chart 1)supporting

confidence: 86%

Heptacoordinated Molybdenum(VI) Complexes of Phenylenediamine Bis(phenolate): A Stable Molybdenum Amidophenoxide Radical

et al. 2013

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“…The tautomeric keto forms of ligands were also indicated by 1 H-NMR spectroscopy since the enolic OH signals of enol forms of ligands were not observed but amide NH signal of keto forms appeared around 10.14-11.19 ppm [17,18]. Furthermore, the observation of strong ν(C=O) absorption bands around 1649-1664 cm −1 in the infrared spectra of the ligands suggest that the ligands are in the keto form in the solid state [19,20] In the case of (H 2 L 1 ) ligand a broad peak is observed in the 3322 cm −1 region which is assigned to phenolic (OH) absorption, while in the case of IR spectra of (H 2 L 2 ) ligand, the peaks observed at 1521 and 1353 cm −1 are attributed to symmetric and asymmetric stretching vibrations of nitro group [17,20], [28]- [31]. The characteristic IR peaks of hydrazone compounds synthesized in this work are given in Table 3.…”

Section: Synthesesmentioning

confidence: 97%

“…probably due to (C=N-N=C) and (C-O) stretching, respectively, suggesting that the NH proton is likely lost via deprotonation induced by the metal and the resulting enolic oxygen and the azomethine nitrogen take place in coordination [19][20][21]. The shift of ν(N-N) stretch of the complexes to higher energy by ∼15-31 cm −1 comparing to that of free ligand can be another evidence for the involvement of azomethine nitrogen in coordination [28,31,32].…”

Section: Synthesesmentioning

confidence: 99%

Synthesis and characterization of bis-acylhydrazone derivatives as tetradentate ligands and their dinuclear metal(II) complexes

Mohammed¹

2012

Per. Pol. Chem. Eng.

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Two novel bis-acylhydrazone where as 1,4-diacetylbenzene bis(4-hydroxy benzoyl hydrazone) H IntroductionHydrazones are the condensation products of hydrazine derivatives with carbonyl compounds, they contain an acyclic group >C=N-N< . It is long since hydrazones and their derivatives, due to their high complexing ability, have attracted the attention of scientists. Depending on various factors (the nature of the hydrazone and the metal atom, reaction conditions, the ratio of reactants etc.) hydrazones form either mono-or polynuclear coordination compounds with metal atoms [1].Aroyl hydrazones and their metal derivatives often possess biological activity and can inhibit enzymatic reactions in the cell [2]-[4]. Edward et al. have shown that replacement of the aromatic group by other moieties in some antibiotics improves their antibiotic activity [5,6]. Apart from biological applications owing to the presence of the toxicologically important N-C=O moiety, hydrazones act as potential donors for different metal ions. These ligands contain an amide bond and are capable of undergoing keto-enol tautomerism: they can coordinate to central metal ions through nitrogen and/or oxygen [7]. Their coordination behaviour also depends upon the pH of the medium, the nature of the substituents and the metal [8].Intensive investigations of the coordination chemistry of dinuclear metal complexes with chelating ligands continue to be stimulated by interest for metallobiomolecules [9], the search for appropriate systems for binding and activating simple molecules, catalysis and magnetic interactions [10,11]. In spite of the greatest effort and success in the study of dinuclear copper(II) complexes, such complexes have still attracted much attention due to their interesting properties and the relative simplicity of their synthesis.Many studies of polyfunctional Schiff bases and monohydrazones as well as their complexes have been carried out [12,13]. Relatively few reports are available on the coordination behaviour of bis-acylhydrazone. These ligands might have interesting ligational features since they contain additional donor sites, i.e. C=O, N-H, azomethine nitrogen atom, etc. Herein, we report the synthesis and spectroscopic studies of dinuclear metal(II) polymeric complexes containing 1,4-diacetylbenzene bis(4-hydroxy benzoylhydrazone) (H 2 L 1 ) and

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“…Dioxomolybdenum(VI) and tungsten(VI) complexes are known to catalyse oxotransfer reactions from DMSO to organic substrates or phosphines. [23,24,[27][28][29]38]. Generally, molybdenum-based catalysts are more active in these reactions than their tungsten counterparts.…”

Section: Scheme 2 Substrates For the Oxidation Reactionsmentioning

confidence: 99%

“…For example, W can replace Mo in sulphite oxidase or nitrate reductase at the same coordination site but with remarkable differences in their behaviour, as these enzymes are less active or completely inactive upon the substitution of Mo by W [16][17][18]. Dioxomolybdenum(VI) complexes with amine bisphenol ligands have generally been prepared from stable and easily available MoO2(acac)2 or MoO2Cl2 and relevant ligand precursors in high yields using simple ligand displacement reactions [19][20][21][22][23][24][25][26], whereas occasional examples employ the use of an acidic solution of (NH4)6Mo7O24•4H2O [27][28][29]. Corresponding W compounds are made under dry conditions using [WO2Cl2(dme)] and ligands as free bases or sodium salts [30,31] or mixing free ligands and [W(eg)3] (eg = ethylene glycol) in alcohol solutions in the presence of ambient moisture [19,32].…”

Section: Introductionmentioning

confidence: 99%

Dioxomolybdenum(VI) and -Tungsten(VI) Amino Bisphenolates as Epoxidation Catalysts

Peuronen

Lehtonen

2016

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Low-cost metallate salts Na2MO4·2H2O (M = molybdenum, tungsten) react with a tridentate amine bisphenol bis(2-hydroxy-3-tert-butyl-5-methylbenzyl)methylamine (H2ONO tBu ) under ambient conditions in acidic methanol solutions. The reactions lead to the formation of isostructural dioxo complexes [MO2(ONO tBu )(MeOH)]·MeOH in convenient yields. Spectral data as well as X-ray analyses reveal these complexes to be isostructural. Both compounds were tested as catalysts for epoxidation of olefins using ciscyclooctene, cyclohexene, norbornene and styrene as substrates and tert-butyl hydroperoxide and hydrogen peroxide as oxidants. The molybdenum complex catalyses selectively the oxidation of cis-cyclooctene and norbornene to corresponding epoxides, whereas oxidation of cyclohexene and styrene lead low yields as the epoxidations were associated with the formation of other oxidation products. Corresponding tungsten complex shows lower activity for epoxidation of norbornene and practically no activity for other olefins. Both complexes can also catalyse the conversion of benzoin to benzil using dimethyl sulphoxide as an oxidant, while the molybdenum complex shows higher activity.

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Synthesis, Structure, and Reactivity of a New Mononuclear Molybdenum(VI) Complex Resembling the Active Center of Molybdenum Oxotransferases

Abstract: The design, synthesis, and structure determination of a pentacoordinate square-pyramidal molybdenum(VI) complex

Cited by 126 publications

References 29 publications

Heptacoordinated Molybdenum(VI) Complexes of Phenylenediamine Bis(phenolate): A Stable Molybdenum Amidophenoxide Radical

Heptacoordinated Molybdenum(VI) Complexes of Phenylenediamine Bis(phenolate): A Stable Molybdenum Amidophenoxide Radical

Synthesis and characterization of bis-acylhydrazone derivatives as tetradentate ligands and their dinuclear metal(II) complexes

Dioxomolybdenum(VI) and -Tungsten(VI) Amino Bisphenolates as Epoxidation Catalysts

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