Kinetics of oxygen-atom transfer reactions involving molybdenum dithiolene complexes †

Lorber, Christian; Plutino, Maria Rosaria; Elding, Lars Ivar; Nordlander, Ebbe

doi:10.1039/a704332e

Cited by 67 publications

(71 citation statements)

References 32 publications

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“…The activation parameters [∆H ϶ ≈ 50 kJ mol -1 ; ∆S ϶ ≈ -(130-160) J mol -1 K -1 ] obtained are compatible with previously determined values for cis-dioxidomolybdenum(VI) complexes and are unexceptional (see Supporting Information). [12,[21][22][23] The bimolecular OAT from 1 involving the sterically demanding substrate PPh 3 proceeds slower, which is essentially ascribed to its larger activation entropy ∆S ϶ (-160 J mol -1 K -1 ). Similar trends were observed by employing cis-dioxidomolybdenum(VI) complexes with other ancillary N,O,S chelate ligands and phosphanes of varying steric demand.…”

Section: Resultsmentioning

confidence: 99%

“…Similar trends were observed by employing cis-dioxidomolybdenum(VI) complexes with other ancillary N,O,S chelate ligands and phosphanes of varying steric demand. [12,[21][22][23] The initially formed phosphorylmolybdenum(IV) complexes 2a-2d are unstable with respect to ligand loss. [16] This is especially pronounced for the larger phosphane oxides (2c, 2d; n = 1, 0).…”

Section: Resultsmentioning

confidence: 99%

“…ate [12] ) are coordinated, which prevents dinucleation. The dinuclear oxido-bridged molybdenum(V) species often represent a thermodynamic minimum and are catalytically less competent in OAT, although OAT has been reported for dinuclear (pyridine-2-thiolato)-and (pyridine-2-selenolato)-molybdenum(V) complexes.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

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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).

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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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

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“…The large negative value for the entropy suggests an associative mechanism similar to previously described systems. [18,55,56] The rate-limiting step is presumably the oxidation of the phosphine indicated by the colour of the reaction solution which remained colourless. Fast oxidation of the reduced molybdenum species by DMSO reforming 2 has been experimentally established (Scheme 2).…”

Section: Catalytic Oxo-transfer Reactivitymentioning

confidence: 99%

Oxygen‐Transfer Reactions of Molybdenum‐ and Tungstendioxo Complexes Containing η²‐Pyrazolate Ligands

et al. 2005

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Dioxomolybdenum and -tungsten compounds containing sterically demanding pyrazolate ligands have been synthesised by treatment of dioxometal halides with the potassium salts of 3,5-ditert-butylpyrazole (t-Bu 2 pzH) and 3,5-di-tert-butyl-4-bromopyrazole (t-Bu 2 -4-BrpzH). The products (5) were characterised by spectroscopic techniques. The X-ray structure of complex 3 reveals a distorted trigonal prismatic geometry with two h 2 -co-ordinated pyrazolate ligands. These high-valent compounds participate in oxygentransfer reactions and catalyse the oxidation of PPh 3 with dimethyl sulphoxide. UV/VIS measurements of the oxo-transfer reactions and the kinetics of the catalytic process are described. By the reaction of 2 with three equivalents of PEt 3 or treatment of [MoOCl 2 -(PMe 3 ) 2 ] with two equivalents of t-Bu 2 pzK mononuclear mono-oxo compounds of the type [MoO(t-Bu 2 -pz) 2 (PR 3 ) 2 ] (R¼ Et 6, R¼ Me 7) were obtained and characterised by X-ray diffraction analyses. This points to biologically relevant mononuclear Mo(IV) intermediates in the catalytic process with this type of complex.

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“…An example of this approach is the use of dianionic maleonitrile (C 4 N 2 S 2 2-) as a ligand. 16 This approach has been used to probe reaction of [Mo VI O 2 ] 2+ centers with tertiary phosphines as well as other substrates. The second approach involves steric control where sterically bulky ligands have been used or by grafting reacting units onto polymeric support which physically inhibit the formation a dinuclear species.…”

Section: Introductionmentioning

confidence: 99%

Design, synthesis, and characterization of a sterically encumbered dioxo molybdenum (VI) core

Sengar¹,

Basu²

2007

Inorganica Chimica Acta

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Dioxo-Mo VI complexes of general formula Tp*MoO 2 (p-SC 6 H 4 Dn) (6a-6c) (where Tp* = hydrotris (3,5-dimethyl-pyrazol-1-yl)borate and Dn= dendritic unit) have been synthesized and characterized by spectroscopy and mass spectrometry. 1 H NMR spectra of the metal complexes indicate that the C s local symmetry about the metal core does not change by the incorporation of dendritic functionality at the thiophenolato ring. Electrochemical data show ∼20 mV change in the redox potential in the complexes with dendritic ligands suggesting a very small perturbation in the redox orbital, which is also supported by small changes in the electronic spectra. The peak-to peak separation (ΔE p ) increases from 125 mV in 6(a) to 240 mV in 6(c), suggesting sluggish electron transfer in molecules with larger dendritic ligands.

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Kinetics of oxygen-atom transfer reactions involving molybdenum dithiolene complexes †

Cited by 67 publications

References 32 publications

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

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

Oxygen‐Transfer Reactions of Molybdenum‐ and Tungstendioxo Complexes Containing η²‐Pyrazolate Ligands

Design, synthesis, and characterization of a sterically encumbered dioxo molybdenum (VI) core

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Kinetics of oxygen-atom transfer reactions involving molybdenum dithiolene complexes †

Cited by 67 publications

References 32 publications

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

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

Oxygen‐Transfer Reactions of Molybdenum‐ and Tungstendioxo Complexes Containing η2‐Pyrazolate Ligands

Design, synthesis, and characterization of a sterically encumbered dioxo molybdenum (VI) core

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Oxygen‐Transfer Reactions of Molybdenum‐ and Tungstendioxo Complexes Containing η²‐Pyrazolate Ligands