Olefin Epoxidation by Methyltrioxorhenium: A Density Functional Study on Energetics and Mechanisms

Gisdakis, Philip; Antonczak, Serge; Köstlmeier, S.; Herrmann, Wolfgang A.; Rösch, Notker

doi:10.1002/(sici)1521-3773(19980904)37:16<2211::aid-anie2211>3.0.co;2-c

Cited by 72 publications

(2 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Implicit solvent contributions are more easily analyzed in such networks, but the limited accuracy typically restricts their use to describing qualitative trends. 40−42 Consequently, most previous computational studies of MTO were limited to unsolvated species 43,44 or, at best, reactions in the presence of a solvent continuum. 32,45,46 Recently, Kuznetsov and Pombeiro computed favorable ligand-exchange transition states involving a single, explicit water molecule, although without comparison to experimental observables.…”

Section: ■ Introductionmentioning

confidence: 99%

“…One approach is to combine ab initio MD and QM/MM methods with importance sampling methods, but such studies are typically limited to single elementary steps. − In addition, involving explicit solvent molecules in a reaction mechanism requires sampling of ensembles of microsolvated states. , These approaches are not yet practical for multistep reaction networks. Implicit solvent contributions are more easily analyzed in such networks, but the limited accuracy typically restricts their use to describing qualitative trends. − Consequently, most previous computational studies of MTO were limited to unsolvated species , or, at best, reactions in the presence of a solvent continuum. ,, Recently, Kuznetsov and Pombeiro computed favorable ligand-exchange transition states involving a single, explicit water molecule, although without comparison to experimental observables . In our recent computational study, we reported that including one explicit water molecule in each ligand-exchange transition state narrows the gap between observed and calculated kinetics by several orders of magnitude .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rate-Enhancing Roles of Water Molecules in Methyltrioxorhenium-Catalyzed Olefin Epoxidation by Hydrogen Peroxide

et al. 2015

View full text Add to dashboard Cite

Olefin epoxidation catalyzed by methyltrioxorhenium (MTO, CH3ReO3) is strongly accelerated in the presence of H2O. The participation of H2O in each of the elementary steps of the catalytic cycle, involving the formation of the peroxo complexes (CH3ReO2(η(2)-O2), A, and CH3ReO(η(2)-O2)2(H2O), B), as well as in their subsequent epoxidation of cyclohexene, was examined in aqueous acetonitrile. Experimental measurements demonstrate that the epoxidation steps exhibit only weak [H2O] dependence, attributed by DFT calculations to hydrogen bonding between uncoordinated H2O and a peroxo ligand. The primary cause of the observed H2O acceleration is the strong co-catalytic effect of water on the rates at which A and B are regenerated and consequently on the relative abundances of the three interconverting Re-containing species at steady state. Proton transfer from weakly coordinated H2O2 to the oxo ligands of MTO and A, resulting in peroxo complex formation, is directly mediated by solvent H2O molecules. Computed activation parameters and kinetic isotope effects, in combination with proton-inventory experiments, suggest a proton shuttle involving one or (most favorably) two H2O molecules in the key ligand-exchange steps to form A and B from MTO and A, respectively.

show abstract

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rate-Enhancing Roles of Water Molecules in Methyltrioxorhenium-Catalyzed Olefin Epoxidation by Hydrogen Peroxide

et al. 2015

View full text Add to dashboard Cite

show abstract

Energetics of the splitting of pyrimidine photodimers induced by electron transfer to rhodium(III) complexes. A quantum chemical study

Rak

Voityuk

R��sch

2000

Int. J. Quant. Chem.

View full text Add to dashboard Cite

Electron transfer (ET) to Rh(III) complexes intercalated in DNA is known to initiate the photorepair of cyclobutane-type pyrimidine photodimers Pyr<>Pyr. We analyzed the energetics of the elementary steps of the resulting splitting reaction Pyr<>Pyr + Rh(III) + hν → Rh(III) + 2Pyr based on results of semiempirical quantum chemical calculations (AM1 and INDO/S). As a check, we also performed B3LYP hybrid density functional calculations on small-and medium-size model systems. The first excited states of the complexes [Rh(NH 3 ) 4 (phi)] 3+ and [Rh(phi) 2 (dmb)] 3+ (phi = 9,10-phenanthrenequinone diimine, dmb = 4,4 -dimethyl-2,2 -bipyridine) exhibit intraligand charge-transfer character, featuring an electron hole in the phenantrene moiety of the phi ligand. Thus, this complex, when intercalating in the π stack of DNA, is ideally suited for reduction by ET from a pyrimidine photodimer in DNA. Environmental effects were found to play a crucial role in preventing thermal ET to a Rh(III) complex, but they favor back ET (BET) from Rh(II) to a pyrimidine cation radical that results from dimer splitting. A driving force for the ET reaction in a polar environment may be gained by increasing the ligand size of the Rh complex. Because of opposite environmental effects on the thermodynamics of the ET and BET reactions, a certain balance has to be kept between various characteristics of the whole system (excitation energy and ligand size of the Rh complex, polarity of the environment) to close the reaction cycle of the overall photorepair by restoring the Rh(III) state.

show abstract

Activity of Peroxo and Hydroperoxo Complexes of TiIV in Olefin Epoxidation: A Density Functional Model Study of Energetics and Mechanism

Yudanov

Gisdakis

Valentin

et al. 1999

Eur. J. Inorg. Chem.

View full text Add to dashboard Cite

Olefin Epoxidation by Methyltrioxorhenium: A Density Functional Study on Energetics and Mechanisms

Cited by 72 publications

References 7 publications

Rate-Enhancing Roles of Water Molecules in Methyltrioxorhenium-Catalyzed Olefin Epoxidation by Hydrogen Peroxide

Rate-Enhancing Roles of Water Molecules in Methyltrioxorhenium-Catalyzed Olefin Epoxidation by Hydrogen Peroxide

Energetics of the splitting of pyrimidine photodimers induced by electron transfer to rhodium(III) complexes. A quantum chemical study

Activity of Peroxo and Hydroperoxo Complexes of TiIV in Olefin Epoxidation: A Density Functional Model Study of Energetics and Mechanism

Contact Info

Product

Resources

About