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Hydrogen Peroxide Activation over Ti IV : What Have We Learned from Studies on Ti‐Containing Polyoxometalates?
Author(s) -
Kholdeeva Oxana A.
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201201396
Subject(s) - chemistry , heterolysis , alkene , protonation , hydrogen peroxide , titanium , context (archaeology) , reaction mechanism , polyoxometalate , medicinal chemistry , catalysis , stereochemistry , photochemistry , organic chemistry , ion , paleontology , biology
This short review paper summarizes recent findings in the field of H 2 O 2 activation over Ti IV centers on the basis of model studies of Ti‐containing polyoxometalates (Ti‐POM) that used both experimental and computational techniques. Alkene epoxidation with H 2 O 2 mediated by two different POMs, the Ti‐monosubstituted Keggin‐type POM, [PTi(OH)W 11 O 39 ] 4– ( 1 ), and the Ti‐disubstituted sandwich‐type POM, [Ti 2 (OH) 2 As 2 W 19 O 67 (H 2 O)] 8– ( 2 ), which contain well‐defined six‐ and five‐coordinate titanium atoms, respectively, as well as some other Ti‐POMs, has been explored to elucidate the role of the Ti IV coordination environment in this reaction. The effect of the Ti‐POM protonation state on the mechanism of H 2 O 2 activation has been analyzed in the context of its relevance to alkene epoxidation. The crucial factors that favor the heterolytic oxidation mechanism that leads to the selective formation of epoxides have been disclosed.