Die Struktur von Amavadin

Berry, Robert E.; Armstrong, Elaine M.; Beddoes, Roy L.; Collison, David; Ertok, S. Nigar; Helliwell, Madeleine; Garner, C. David

doi:10.1002/(sici)1521-3757(19990315)111:6<871::aid-ange871>3.3.co;2-r

Cited by 2 publications

(8 citation statements)

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“…The DFT structural data reveal that for all isomers of MLH 2 There are only a few complexes with (O=)VÀO phenolate (trans) bonds with structures characterized by X-ray diffraction, [76] and the calculated (O=)VÀO phenolate (trans) distances are intermediate between those of the cis form, when the O phenolate is in the equatorial plane (approximately 1.9 ä), and those of the compounds containing neutral oxygen donors, including the HO phenolate group (approximately 2.2±2.4 ä). [73,74] Thus, the trans influence of the O oxo ligand is still expressed when one compares the lengths~1.9 and~2.1 ä.…”

Section: Ligand Protonation By Ph-potentiometry and 1 H Nmr Spectroscmentioning

confidence: 99%

“…Vanadium is a bioessential element that is found in remarkably high concentrations in marine ascidians, [1] certain mushrooms, [2] and polychaete worms. [3] Three types of vanadiumcontaining enzymes are known: vanadium nitrogenases, [4] vanadium-dependent haloperoxidases, [5] and vanadium-containing nitrate reductases.…”

Section: Introductionmentioning

confidence: 97%

“…[11,12] To date, only [V IV O(sal 2 en)] has been tested in vivo for insulin-mimetic activity. Pyridoxal and pyridoxamine are forms of vitamin B 6 , known cofactors required by many enzymes.…”

Section: Introductionmentioning

confidence: 99%

“…This may yield the half SB (and one aldehyde), or proceed further to the ethylenediamine and a second molecule of pyridoxal. The complex [(VO 2 ) 2 (pyren) 2 ]¥2 H 2 O was obtained from solutions containing H 2 pyr 2 en and VOSO 4 , where Hpyren is the ™half∫ SB 3 (see Scheme 1). However, this instability was overcome by reduction of the SB to give an amine: H 2 Rpyr 2 en (2).…”

Section: Introductionmentioning

confidence: 99%

“…The totally protonated forms of 1 and 2 correspond to H 6 L 4 + , and all protonation constants were determined by pH-potentiometric and Supporting information for this article is available on the WWW under http://www.chemeurj.org/ or from the author. Some additional X-ray data for 1, 2, 4, and 9 (SI-1); further discussion of IR spectra (SI-2); UV/Vis absorption data for the ligands and V IV O complexes prepared in this work (SI-3); determination of the dissociation constants of [H 6 R(pyr) 2 …”

mentioning

confidence: 99%

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N,N′‐Ethylenebis(pyridoxylideneiminato) and N,N′‐Ethylenebis(pyridoxylaminato): Synthesis, Characterization, Potentiometric, Spectroscopic, and DFT Studies of Their Vanadium(IV) and Vanadium(V) Complexes

Correia¹,

Pessoa²,

Duarte³

et al. 2004

Chemistry A European J

128

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The Schiff base N,N'-ethylenebis(pyridoxylideneiminato) (H 2 pyr 2 en, 1) was synthesized by reaction of pyridoxal with ethylenediamine; reduction of H 2 pyr 2 en with NaBH 4 yielded the reduced Schiff base N,N'-ethylenebis-(pyridoxylaminato) (H 2 Rpyr 2 en, 2); their crystal structures were determined by X-ray diffraction. The totally protonated forms of 1 and 2 correspond to H 6 L 4 + , and all protonation constants were determined by pH-potentiometric and Supporting information for this article is available on the WWW under http://www.chemeurj.org/ or from the author. Some additional X-ray data for 1, 2, 4, and 9 (SI-1); further discussion of IR spectra (

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Section: Ligand Protonation By Ph-potentiometry and 1 H Nmr Spectroscmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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N,N′‐Ethylenebis(pyridoxylideneiminato) and N,N′‐Ethylenebis(pyridoxylaminato): Synthesis, Characterization, Potentiometric, Spectroscopic, and DFT Studies of Their Vanadium(IV) and Vanadium(V) Complexes

Correia¹,

Pessoa²,

Duarte³

et al. 2004

Chemistry A European J

128

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Single‐Pot Conversion of Methane into Acetic Acid in the Absence of CO and with Vanadium Catalysts Such as Amavadine

Reis¹,

Silva²,

Palavra³

et al. 2003

Angew Chem Int Ed

126

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Despite current interest in the biological roles of vanadium, its application in catalysis is still an underdeveloped field of research.[1] We have already reported that amavadine, a natural vanadium complex present in some Amanita fungi and whose biological function is still unknown, can exhibit haloperoxidase-and peroxidase-type activities and act as a catalyst for the oxidation of some biological thiols, [2] as well as for the peroxidative halogenation, hydroxylation, and oxofunctionalization of alkanes and aromatic compounds. [3] Following this work, we have been searching for other reactions that could be catalyzed by this and related V complexes, in particular the conversion of methane-the main component of natural gas and the most abundant and least reactive alkane-into functionalized products with added commercial value.[4] Recently attention has focused on the metal-catalyzed transformation of CH 4 and CO into acetic acid, [5][6][7][8][9][10][11] as well as the formation of carbonylated products without requiring the use of noxious CO, such as the conversion of CH 4 into methyl esters [12] and into acetic acid (and methanol).[9] The latter, the reaction of CH 4 and CO 2 catalyzed by NaVO 3 /pyrazine-2-carboxylic acid (in the presence of H 2 O 2 in aqueous solution), occurs in very low yield based on CH 4 (ca. 0.01 %) and at a considerable pressure (50 bar) of this gas, although at low temperature (40 8C).[9]The reaction also proceeds with CO, which apparently is the carbonylating agent even when CO 2 is used (CO is then formed by reduction of CO 2 by methyl and/or hydroxyl radicals).[9] We now report the unprecedented (to our knowledge) conversion of CH 4 into CH 3 COOH in the absence of either CO or CO 2 , in a novel single-pot catalytic reaction [Eq. (1)] under considerably mild conditions and in high yields. Table 1, and typical conditions include conducting the reaction in CF 3 COOH at 80 8C with molar ratios of CH 4 :V catalyst and K 2 S 2 O 8 :V catalyst of 46:1 (corresponding to CH 4 pressure of 5 atm) and 200:1, respectively. Usually the yields were determined after a reaction time of 20 h, but often much shorter times were sufficient to attain close values (see entries 1 and 11 for yields obtained after 2 h; the former is 92 % of that in entry 2 obtained after 20 h). The most active catalysts, which can give yields over 50 % and TONs close to 30, are complex 1 within the type

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Die Struktur von Amavadin

Cited by 2 publications

References 0 publications

N,N′‐Ethylenebis(pyridoxylideneiminato) and N,N′‐Ethylenebis(pyridoxylaminato): Synthesis, Characterization, Potentiometric, Spectroscopic, and DFT Studies of Their Vanadium(IV) and Vanadium(V) Complexes

N,N′‐Ethylenebis(pyridoxylideneiminato) and N,N′‐Ethylenebis(pyridoxylaminato): Synthesis, Characterization, Potentiometric, Spectroscopic, and DFT Studies of Their Vanadium(IV) and Vanadium(V) Complexes

Single‐Pot Conversion of Methane into Acetic Acid in the Absence of CO and with Vanadium Catalysts Such as Amavadine

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