Epoxidation of Alkenes with H₂O₂ Catalyzed by Dititanium‐Containing 19‐Tungstodiarsenate(III): Experimental and Theoretical Studies

Abstract

(1), which contains five-coordinate Ti atoms. The results of product and kinetics studies support a mechanism that involves a reversible interaction between H 2 O 2 and the Ti-OH group of 1 to produce a titanium hydroperoxo complex followed by electrophilic oxygen atom transfer from the hydroperoxo ligand to the alkene substrate in the rate-limiting step. The effect of the alkene substrate nature has been investigated at the DFT

Hydrogen Peroxide Activation over TiIV: What Have We Learned from Studies on Ti‐Containing Polyoxometalates?

“…The presence of the allylic products points to the homolytic activation of the oxidant. Similar product distributions were found for various POMs that contained multiple Ti centers in a hexacoordinate environment 30,32…”

“…A breakthrough in understanding of the crucial factors that favor heterolytic activation of H 2 O 2 by Ti IV came with the synthesis of 2 by Kortz's group30 followed by experimental and theoretical studies on this POM 31,32,37. Polyanion 2 comprises two ( B‐ α‐As III W 9 O 33 ) Keggin moieties linked by means of two square‐pyramidal [Ti(OH)] 3+ groups and one octahedral [WO(H 2 O)] 4+ fragment (see Figure 1 for the structure).…”

Recent advances of polyoxometalate-catalyzed selective oxidation based on structural classification

“…The consecutive investigations by Carbó, Kholdeeva, Poblet et al (Antonova et al, 2010;Donoeva et al, 2010;Jimé nez-Lozano et al, 2012 clarified the mechanism for the activation of hydrogen peroxide by Keggin-type Ti IV -containing POMs. Firstly, they discovered the activity of the Timonosubstituted POM [PTi(OH)W 11 O 39 ] 4À (1a) and the Tidisubstituted sandwich-type POM [Ti 2 (OH) 2 As 2 W 19 O 67 -(H 2 O)] 8À (1b; Fig.…”

“…For the cases where POM structures contain large voids and the exact amount of solvent located in the voids is unidentified due to their high disorder and small residual peaks, the SQUEEZE option (Spek, 2015) in PLATON can remove the contribution of the solvent molecules (Hu et al, 2017). Regarding DFT calculations, algorithms and methods such as the ONIOM algorithm, the Davidson algorithm, the NBO method and the SOPERT method have displayed their own specialities in elucidating structure-performance relationships (Donoeva et al, 2010;De Waele et al, 2016).…”

Computational study on chain pathways for oxygen atom transfer catalyzed by a methyl(dithiolate) thiorhenium(V) compound

“…The metal center cycling between the VI (d 0 ) and IV(d 2 ) oxidation states. Other metal oxo (M=O, M=V, Fe, Ti, Mn and Cr) moieties have also received an interest due to catalytic applications in oxidation reactions [4][5][6][7][8][9][10].…”