Tetrahydropterin Reactions of Dioxo-Molybdenum(6+) Complexes: Does Redox Occur?

Burgmayer, Sharon J. Nieter; Arkin, Michelle R.; Bostick, Laura; Dempster, Sara; Everett, Kristin; Layton, Heather L.; Paul, Kateri E.; Rogge, Cory; Rheingold, Arnold L.

doi:10.1021/ja00126a020

Cited by 29 publications

(55 citation statements)

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“…We previously reported how 4 is oxidized by ferrocenium or hydrogen peroxide to the Mo(5+) complex [Tp * Mo(O)(pyrrolo-S 2 BMOQO)] + 5 . 16 The reaction is a striking one to observe visually as the intensely blue solution of 4 becomes bright cherry red on addition of oxidant as the Mo(5+) complex 5 forms. Solutions of 5 are not stable and they slowly revert to the Mo(4+) as indicated by color change to blue.…”

Section: Results and Analysismentioning

confidence: 99%

Study of Molybdenum(4+) Quinoxalyldithiolenes as Models for the Noninnocent Pyranopterin in the Molybdenum Cofactor

et al. 2011

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A model system for the molybdenum cofactor has been developed that illustrates the non-innocent behavior of a N-heterocycle appended to a dithiolene chelate on molybdenum. The pyranopterin of the molybdenum cofactor is modeled by a quinoxalyl-dithiolene ligand (S2BMOQO) formed from reaction of a molybdenum tetrasulfide and a quinoxalyl alkyne. The resulting complexes TEA[Tp*MoX(S2BMOQO)] (1, X = S; 3, X = O; TEA = tetraethylammonium; Tp* = hydrotris(3,5-dimethylpyrazolyl)borate) undergo a dehydration-driven intramolecular cyclization within the quinoxalyl-dithiolene forming Tp*MoX(pyrrolo-S2BMOQO) (2, X= S; 4, X= O). 4 can be oxidized by one electron to produce the Mo(5+) complex 5. In a preliminary report of this work evidence from X-ray crystallography, electronic absorption and resonance Raman spectroscopies, and DFT bonding calculations revealed that 4 possesses an unusual asymmetric dithiolene chelate with significant thione-thiolate character. The results described here provide a detailed description of the reaction conditions that lead to formation of 4. Data from cyclic voltammetry, additional DFT calculations and several spectroscopic methods (infrared, electronic, resonance Raman, electron paramagnetic resonance) have been used to characterize the properties of members in this suite of five Mo(S2BMOQO) complexes and further substantiate the highly electron-withdrawing character of the pyrrolo-S2BMOQO ligand in 2 and 4. This study of the unique non-innocent ligand S2BMOQO provides examples of the roles that the N-heterocycle pterin can play as an essential part of the molybdenum cofactor. The versatile nature of dithiolene appended by heterocycles may aid in modulating the redox processes of the molybdenum center during the course of enzyme catalysis.

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Section: Results and Analysismentioning

confidence: 99%

Study of Molybdenum(4+) Quinoxalyldithiolenes as Models for the Noninnocent Pyranopterin in the Molybdenum Cofactor

et al. 2011

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“…These results suggested that oxidation/reduction states of the pterin were involved in the Mo oxidation state during substrate turnover. However, more recently [82], the same authors reinterpreted those results on the basis of isolated complexes where molybdenum is found to bind directly to the pterin. Nevertheless, extrapolations from these model systems to molybdenum-containing enzymes were not satisfactory.…”

Section: Structure and Environment Of The Metal Centersmentioning

confidence: 97%

“…Nevertheless, extrapolations from these model systems to molybdenum-containing enzymes were not satisfactory. Although the synthesis of such complexes of molybdenum coordinated to pterin species has deserved much attention [35] and has often been successful [68,82,89], the relationship to the reaction mechanism of molybdenum hydroxylases is not clear.…”

Section: Structure and Environment Of The Metal Centersmentioning

confidence: 99%

Structure and function of the xanthine-oxidase family of molybdenum enzymes

Romão

Huber

1998

Structure and Bonding

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This work gives an account of the recent achievements which have contributed towards the understanding of the structure and function of the xanthine oxidase family of enzymes-the molybdenum hydroxylases. It is based essentially on the crystallographic data of the aldehyde oxido-reductase from Desulfovibrio (D.) gigas, a member of that family, whose structure is described in detail. Comparisons are made, whenever appropriate, with spectroscopic, kinetic and model compound studies. Mechanistic implications of the crystal structure of the D. gigas enzyme are considered and extended to the xanthine oxidase family.

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“…For molybdenum complexes with pterin ligands, the structural criteria for this assignment were reported in the studies. 154,155 In particular, UV-Vis and photoelectron spectroscopy demonstrated that the Mo V (H 3 pterin . ) structure is preferable for the molybdenum complex with tetrahydropterin (a fragment of the complex is shown).…”

Section: Pterin Complexesmentioning

confidence: 99%

Metal complexes with non-innocent ligands

Butin¹,

Белоглазкина²,

Зык³

2005

Russ. Chem. Rev.

125

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The review summarises data on transition metal com-The review summarises data on transition metal complexes with the so-called non-innocent ligands. The specific plexes with the so-called non-innocent ligands. The specific feature of these complexes is that the oxidation state of the central feature of these complexes is that the oxidation state of the central metal atom and the electronic structure of the ligands are metal atom and the electronic structure of the ligands are impossible to determine impossible to determine a priori a priori and unambiguously. The results and unambiguously. The results of experimental studies (spectroscopic, electrochemical, X-ray of experimental studies (spectroscopic, electrochemical, X-ray diffraction) of complexes with various non-innocent ligands are diffraction) of complexes with various non-innocent ligands are analysed. Particular attention is given to their structures and analysed. Particular attention is given to their structures and redox properties. The bibliography includes 208 references redox properties. The bibliography includes 208 references. .

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Tetrahydropterin Reactions of Dioxo-Molybdenum(6+) Complexes: Does Redox Occur?

Cited by 29 publications

References 0 publications

Study of Molybdenum(4+) Quinoxalyldithiolenes as Models for the Noninnocent Pyranopterin in the Molybdenum Cofactor

Study of Molybdenum(4+) Quinoxalyldithiolenes as Models for the Noninnocent Pyranopterin in the Molybdenum Cofactor

Structure and function of the xanthine-oxidase family of molybdenum enzymes

Metal complexes with non-innocent ligands

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