Rhenium(V) Oxo-Alkoxide Complexes: Syntheses and Oxidation to Aldehydes

DuMez, Darin D.; Mayer, James M.

doi:10.1021/ic00129a026

Cited by 40 publications

(28 citation statements)

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“…The mechanism in Scheme has since then been substantiated by additional experimental investigations . DuMez and Mayer have most recently demonstrated that a hydride transfer mechanism similar to that of Scheme is operative in processes where aldehydes are eliminated from rhenium(V) oxo alkoxide complexes. Possible structures for the transition states TS1 and TS2 in Scheme have also been postulated.…”

Section: Introductionmentioning

confidence: 91%

Theoretical Study of the Oxidation of Alcohol to Aldehyde by d⁰ Transition-Metal−Oxo Complexes: Combined Approach Based on Density Functional Theory and the Intrinsic Reaction Coordinate Method

Deng

Ziegler

1997

Organometallics

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A combined density functional (DF) and intrinsic reaction coordinate (IRC) method has been applied to the mechanistic study of methanol oxidization to formaldehyde by the d0 transition-metal−oxo complexes MO2X2 (M = Cr, Mo, X = Cl; M = Ru, X = O). A two-step mechanism was investigated. The two steps involve addition of the methanol OH bond to an MO linkage to form a M−methoxy complex, MO2X2 + CH3OH = M(O)(OH)Cl2(OCH3) (step 1), and the elimination of formaldehyde from the M−methoxy complex to yield the final products, M(O)(OH)Cl2(OCH3) = M(OH)2X2 + CH2O (step 2). The calculated vibrational adiabatic intrinsic barriers were 23.7 kcal/mol (Cr), 16.2 kcal/mol (Mo), and 21.4 kcal/mol (Ru) for the addition process (1), as well as 23.1 kcal/mol (Cr), 33.3 kcal/mol (Mo), and 7.4 kcal/mol (Ru) for the elimination step (2). The enthalpies of the overall oxidation process were computed to be 3.1 kcal/mol (Cr), 41.9 kcal/mol (Mo), and −1.9 kcal/mol (Ru). The IRC trajectories revealed that reaction 1 is initiated by the formation of the weaker adduct CH3OH−MO2X2 between the initial reactants, whereas reaction 2 results in the strong adduct CH2O−M(OH)2X2 between final products. It is concluded that only the chromium and ruthenium oxo complexes are efficient reagents for the conversion of methanol to formaldehyde.

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Section: Introductionmentioning

confidence: 91%

Theoretical Study of the Oxidation of Alcohol to Aldehyde by d⁰ Transition-Metal−Oxo Complexes: Combined Approach Based on Density Functional Theory and the Intrinsic Reaction Coordinate Method

Deng

Ziegler

1997

Organometallics

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“…The mechanism of the oxidation reactions likely proceeds by initial oxygen-atom transfer to give a reactive rhenium(VII) dioxo cation, [Tp*Re(O) 2 H][OTf] ( A in Scheme ), by analogy with previous studies on TpReO(X)OTf compounds (X = alkyl, aryl, alkoxy, and halide 9c ). Intermediate A could then be deprotonated directly by NPh 3 , py, or OTf - (the lower pathway in Scheme ), but it seems unlikely that A would be such a strong acid .…”

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confidence: 95%

Synthesis and Reactions of Rhenium(V) Oxo−Hydride Complexes

et al. 1998

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“…This approach of adding an oxygen atom donor to a metal center that bears an oxidizable organic group has been valuable in the discovery of the first well-defined phenyl-tooxo migration reaction 10 and other reactions. 11 Experimental Section General Considerations. All experiments were performed under an inert atmosphere using standard vacuum, Schlenk, and glovebox techniques, except where noted.…”

Section: Introductionmentioning

confidence: 99%

Selective Oxidation of the Alkyl Ligand in Rhenium(V) Oxo Complexes

DuMez

Mayer

1996

J. Am. Chem. Soc.

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Rhenium(V) oxo alkyl triflate compounds (HBpz3)ReO(R)OTf [R = Me (4), Et (5), n-Bu (6); HBpz3 = hydrotris(1-pyrazolyl)borate; OTf = OSO2CF3, triflate] are formed on sequential reaction of (HBpz3)ReOCl2 with dialkyl zinc reagents and AgOTf. These triflate compounds are rapidly oxidized at ambient temperatures by oxygen atom donors pyridine N-oxide (pyO) and dimethyl sulfoxide (DMSO) to give (HBpz3)ReO3 (7) and the corresponding aldehyde. In the cases of 5 and 6 this transformation is quantitative. The addition of 2,6-lutidine to a low-temperature oxidation of 5 by DMSO redirects the reaction to form cis-2-butene instead of acetaldehyde. These oxidation reactions do not proceed through alkoxide intermediates, as shown by independent studies of alkoxide oxidations. Reaction of 5 with pyO or DMSO at −47 °C results in the formation of intermediates which are assigned as ylide or “trapped-carbene” complexes [(HBpz3)ReO(OH){CH(L)CH3}]OTf (L = py (8) or SMe2 (9), respectively). Mechanistic studies and analogies with related systems suggest that oxygen atom transfer to 4-6 forms [(HBpz3)ReO2R]+. Transfer of an α-hydrogen from the alkyl group to an oxo ligand then forms an alkylidene complex which is trapped by SMe2 or py to give the observed intermediates. Further oxidation of the ylide complex gives the aldehyde.

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Rhenium(V) Oxo-Alkoxide Complexes: Syntheses and Oxidation to Aldehydes

Cited by 40 publications

References 2 publications

Theoretical Study of the Oxidation of Alcohol to Aldehyde by d⁰ Transition-Metal−Oxo Complexes: Combined Approach Based on Density Functional Theory and the Intrinsic Reaction Coordinate Method

Theoretical Study of the Oxidation of Alcohol to Aldehyde by d⁰ Transition-Metal−Oxo Complexes: Combined Approach Based on Density Functional Theory and the Intrinsic Reaction Coordinate Method

Synthesis and Reactions of Rhenium(V) Oxo−Hydride Complexes

Selective Oxidation of the Alkyl Ligand in Rhenium(V) Oxo Complexes

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Rhenium(V) Oxo-Alkoxide Complexes: Syntheses and Oxidation to Aldehydes

Cited by 40 publications

References 2 publications

Theoretical Study of the Oxidation of Alcohol to Aldehyde by d0 Transition-Metal−Oxo Complexes: Combined Approach Based on Density Functional Theory and the Intrinsic Reaction Coordinate Method

Theoretical Study of the Oxidation of Alcohol to Aldehyde by d0 Transition-Metal−Oxo Complexes: Combined Approach Based on Density Functional Theory and the Intrinsic Reaction Coordinate Method

Synthesis and Reactions of Rhenium(V) Oxo−Hydride Complexes

Selective Oxidation of the Alkyl Ligand in Rhenium(V) Oxo Complexes

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Theoretical Study of the Oxidation of Alcohol to Aldehyde by d⁰ Transition-Metal−Oxo Complexes: Combined Approach Based on Density Functional Theory and the Intrinsic Reaction Coordinate Method

Theoretical Study of the Oxidation of Alcohol to Aldehyde by d⁰ Transition-Metal−Oxo Complexes: Combined Approach Based on Density Functional Theory and the Intrinsic Reaction Coordinate Method