Molybdenum(V) sites in xanthine oxidase and relevant analog complexes: comparison of molybdenum-95 and sulfur-33 hyperfine coupling

Wilson, G. L.; Greenwood, Richard; Pilbrow, John R.; Spence, J. T.; Wedd, Anthony G.

doi:10.1021/ja00018a014

Cited by 104 publications

(113 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…S angle of 107.33(14)°is also greater than that of Tp iPr MoOS-(OC6 H 4 s Bu) (103.7(2)°), 4 consistent with trends observed in dioxo-Mo(VI) and -Mo(V) complexes. 53,54 Significantly, the Mo ---S bond in 9 is much shorter than that reported for PPh 4 [MoOS(L-N 2 S 2 )] (2.36 Å by EXAFS) 1 but close to the range established for XnO-VR (2.0 ± 0.2 Å).…”

supporting

confidence: 80%

d¹ Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series

Doonan¹,

Gourlay²,

Nielsen³

et al. 2015

Inorg. Chem.

View full text Add to dashboard Cite

Reaction of Tp(iPr)Mo(VI)OS(OAr) with cobaltocene in toluene results in the precipitation of brown, microcrystalline oxosulfido-Mo(V) compounds, [CoCp2][Tp(iPr)Mo(V)OS(OAr)] (Cp(-) = η(5)-C5H5(-), Tp(iPr)(-) = hydrotris(3-isopropylpyrazol-1-yl)borate, OAr(-) = phenolate or 2-(s)Bu, 2-(t)Bu, 3-(t)Bu, 4-(s)Bu, 4-Ph, 3,5-(s)Bu2, 2-CO2Me, 2-CO2Et or 2-CO2Ph derivative thereof). The compounds are air- and water-sensitive and display ν(Mo═O) and ν(Mo[Formula: see text]S) IR absorption bands at ca. 890 and 435 cm(-1), respectively, 20-40 cm(-1) lower in energy than the corresponding bands in Tp(iPr)MoOS(OAr). They are electrochemically active and exhibit three reversible cyclovoltammetric waves (E(Mo(VI)/Mo(V)) = -0.40 to -0.66 V, E([CoCp2](+)/CoCp2) = -0.94 V and E(CoCp2/[CoCp2](-)) = -1.88 V vs SCE). Structural characterization of [CoCp2][Tp(iPr)MoOS(OC6H4CO2Et-2)]·2CH2Cl2 revealed a distorted octahedral Mo(V) anion with Mo═O and Mo[Formula: see text]S distances of 1.761(5) and 2.215(2) Å, respectively, longer than corresponding distances in related Tp(iPr)MoOS(OAr) compounds. The observation of strong S(1s) → (S(3p) + Mo(4d)) S K-preedge transitions indicative of a d(1) sulfido-Mo(V) moiety and the presence of short Mo═O (ca. 1.72 Å) and Mo[Formula: see text]S (ca. 2.25 Å) backscattering contributions in the Mo K-edge EXAFS further support the oxosulfido-Mo(V) formulation. The compounds are EPR-active, exhibiting highly anisotropic (Δg 0.124-0.150), rhombic, frozen-glass spectra with g1 close to the value observed for the free electron (ge = 2.0023). Spectroscopic studies are consistent with the presence of a highly covalent Mo[Formula: see text]S π* singly occupied molecular orbital. The compounds are highly reactive, with reactions localized at the terminal sulfido ligand. For example, the compounds react with cyanide and PPh3 to produce thiocyanate and SPPh3, respectively, and various (depending on solvent) oxo-Mo(V) species. Reactions with copper reagents also generally lead to desulfurization and the formation of oxo-Mo(V) or -Mo(IV) complexes.

show abstract

supporting

confidence: 80%

d¹ Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series

Doonan¹,

Gourlay²,

Nielsen³

et al. 2015

Inorg. Chem.

View full text Add to dashboard Cite

show abstract

“…[39] These absorptions are found at lower energy than those of the corresponding neutral molybdenum(VI) complex 1 featuring ν = 930, 902 cm -1 . [16] DFT calculations of models of 1 and 1 - [19] predict a shift (scaled by 0.9614 [40] ) from ν = 940, 914 cm [41] The EPR signal of the Mo V state of formate dehydrogenase is also reported to be split by proton coupling with A iso ( 1 H) = 16 G. [42] The anisotropic EPR spectra of frozen solutions of 1 -, 7 and 8 are shown in Figures 7, 8, and 9. All observed g values are Ͻ 2.0, and hyperfine coupling to 95/97 Mo isotopes is also detected.…”

Section: One-electron Oxidation Of 5a-5c (Momentioning

confidence: 97%

“…Yield: 496 mg (60 %). C 41 + . Due to the presence of OPMePh 2 , which could not be separated by precipitation or recrystallization (chromatography was also unsuccessful due to decomposition), satisfying elemental analyses could not be obtained.…”

Section: Synthesis Of 5cmentioning

confidence: 99%

Oxidomolybdenum(IV), ‐(V), ‐(VI) Complexes with Relevance to Molybdenum Enzymes: Oxygen Atom Transfer, Redox Chemistry and EPR Spectroscopy

Heinze

Fischer

2010

Eur J Inorg Chem

View full text Add to dashboard Cite

The cis‐dioxidomolybdenum(VI) complex Mo(NN′)2O2 (1) [(NN′) = N‐(4‐hydroxyphenyl)‐2‐pyrrolatocarbaldimine] transfers one oxygen atom to phosphanes PMenPh3–n (n = 0–3) to give quantitatively the respective phosphane oxides OPMenPh3–n (OAT, oxygen atom transfer). The kinetics of these OAT reactions has been investigated spectrophotometrically. When offering excess PMenPh3–n (n = 1–3), oxido(phoshane)molybdenum(IV) complexes Mo(NN′)2O(PMenPh3–n) 5a–5c are isolated and characterized by multinuclear NMR spectroscopy (1H, 13C, 31P, 15N), IR spectroscopy, UV/Vis spectroscopy and mass spectrometry. The redox chemistry of the molybdenum(IV) complexes 5a–5c and of molybdenum(VI) complex 1 has been probed by preparative one‐electron oxidation and reduction, respectively, in combination with EPR spectroscopy under strictly anhydrous conditions. The reactivity of the resulting MoV species (ligand substitution, protonation, silyation) has been investigated to shed further light onto the biomimetic catalytic cycle of OAT from water to substrates in combination with two coupled electron proton transfer reactions (CEPT).

show abstract

“…As the g-tensor orientations were unknown, the eigenvectors of the Mo(V) g-tensor for the slow signal were assigned by symmetry considerations (see Table 1), assuming that the g//axis is lying along the normal to the equatorial ligand plane. This assumption is based on the previous EPR results that showed that the slow signal is associated with a Mo(V) site with C s or C 2 point symmetry [51] and also on results obtained from single crystal EPR spectroscopy and molecular orbital calculations on a nearly square pyramidal coordination Mo(V) complex in which the g//axis is lying nearly along the apical bond [52]. The principal directions of FeS 1 were also chosen from symmetry considerations, but permutations for the x, y, and z values were performed until the best agreement with the experimental spectrum was reached.…”

Section: Analysis Of the Mo(v)-fes 1 Magnetic Couplingmentioning

confidence: 99%

Isotropic exchange interaction between Mo and the proximal FeS center in the xanthine oxidase family member aldehyde oxidoreductase from Desulfovibrio gigas on native and polyalcohol inhibited samples: an EPR and QM/MM study

et al. 2014

View full text Add to dashboard Cite

Aldehyde oxidoreductase from Desulfovibrio gigas (DgAOR) is a homodimeric molybdenum-containing protein that catalyzes the hydroxylation of aldehydes to carboxylic acids and contains a Mo-pyranopterin active site and two FeS centers called FeS 1 and FeS 2. The electron transfer reaction inside DgAOR is proposed to be performed through a chemical pathway linking Mo and the two FeS clusters involving the pyranopterin ligand. EPR studies performed on reduced as-prepared DgAOR showed that this pathway is able to transmit very weak exchange interactions between Mo(V) and reduced FeS 1. Similar EPR studies but performed on DgAOR samples inhibited with glycerol and ethylene glycol showed that the value of the exchange coupling constant J increases ~2 times upon alcohol inhibition. Structural studies in these DgAOR samples have demonstrated that the Mo-FeS 1 bridging pathway does not show significant differences, confirming that the changes in J observed upon inhibition cannot be ascribed to structural changes associated neither with pyranopterin and FeS 1 nor with changes in the electronic structure of FeS 1, as its EPR properties remain unchanged. Theoretical calculations indicate that the changes in J detected by EPR are related to changes in the electronic structure of Mo(V) determined by the replacement of the OHx labile ligand for an alcohol molecule. Since the relationship between electron transfer rate and isotropic exchange interaction, the present results suggest that the intraenzyme electron transfer process mediated by the pyranopterin moiety is governed by a Mo ligand-based regulatory mechanism.

show abstract

Molybdenum(V) sites in xanthine oxidase and relevant analog complexes: comparison of molybdenum-95 and sulfur-33 hyperfine coupling

Cited by 104 publications

References 7 publications

d¹ Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series

d¹ Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series

Oxidomolybdenum(IV), ‐(V), ‐(VI) Complexes with Relevance to Molybdenum Enzymes: Oxygen Atom Transfer, Redox Chemistry and EPR Spectroscopy

Isotropic exchange interaction between Mo and the proximal FeS center in the xanthine oxidase family member aldehyde oxidoreductase from Desulfovibrio gigas on native and polyalcohol inhibited samples: an EPR and QM/MM study

Contact Info

Product

Resources

About

Molybdenum(V) sites in xanthine oxidase and relevant analog complexes: comparison of molybdenum-95 and sulfur-33 hyperfine coupling

Cited by 104 publications

References 7 publications

d1 Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series

d1 Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series

Oxidomolybdenum(IV), ‐(V), ‐(VI) Complexes with Relevance to Molybdenum Enzymes: Oxygen Atom Transfer, Redox Chemistry and EPR Spectroscopy

Isotropic exchange interaction between Mo and the proximal FeS center in the xanthine oxidase family member aldehyde oxidoreductase from Desulfovibrio gigas on native and polyalcohol inhibited samples: an EPR and QM/MM study

Contact Info

Product

Resources

About

d¹ Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series

d¹ Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series