Homogeneous catalysis by transition metal oxygen anion clusters

Towards robust alkane oxidation catalysts: electronic variations in non-heme iron(ii) complexes and their effect in catalytic alkane oxidation

“…[1][2][3][4] Despite several industrial applications such as the oxidation of cyclohexane and p-xylene, which use O 2 as the oxidant and manganese or cobalt based catalysts, the development of practical oxidation catalysts and a thorough mechanistic understanding of alkane oxidation processes continue to provide great challenges in catalysis research. A number of different classes of alkane oxidation catalysts have been developed during the last 50 years, including the cobalt and manganese acetate catalyst systems used industrially, 5 the heme-based iron complexes containing porphyrin-type ligands used in nature, 6,7 polyoxometalates [8][9][10] and more recently, non-heme iron based catalyst systems. [11][12][13][14][15][16][17] The metal catalysts are typically combined with oxidants, which can have different oxo transfer abilities 18 , for example H 2 O 2 , O 2 , ClO -, PhIO, O 3 or N 2 O, whereby the first two oxidants are economically and environmentally the most attractive oxidants.…”

Lewis Base Catalytic Properties of [Nb10O28]6− for CO2 Fixation to Epoxide: Kinetic and Theoretical Studies

“…This trend is in parallel with that in the oxygen exchange rate ((O2, O3, O6) > O4 > O5 > O1) of [Nb 10 O 28 ] 6À in neutrala queous solutionw hich gives am easureo fb asicity of oxygen sites. [30] Figure 5(b) shows that the adsorption energy increases with the increase in negative charge of CO 2 [31] which acts as trong Lewis acid [32] due to tetrahedral [NbO 4 ] units. [33,34] Experimental Section Chemicals.…”

“…[1] POMs are widely used as acid catalysts, oxidation catalysts, andp hotocatalysts because of the controllability of actives ites and high stability. [2][3][4][5] Recent studies reported that [WO 4 ] 2À acted as aL ewis base catalyst for CO 2 fixation. [6][7][8] It was also reported that [gHGeW 10 O 36 ] 7À showedB rønsted base catalysis for Knoevenagel condensation reactions.…”

“…Typical procedure for CO 2 fixation under P CO2 < 0.1 MPa at atmospheric pressure was as follows. In at est tube, (TBA) 6 [Nb 10 O 28 ]( 14.2 mg, 5.0 mmol) was dissolved in styrene oxide (SO, 500 mL, 4.41 mmol) and ab alloon filled with ag as mixture of CO 2 and Ar with at otal pressure of 0.1 MPa was connected. The mixture was degassed by freeze-pump-thaw cycle.…”

Heterogeneous Catalytic Oxidation of Cyclohexane with H2O2 Catalyzed by Cs- and TBA-salts of Cu- and Mn-Polyoxotungstates on MCM-41

“…1 many reactions because of their thermal and chemical stability and the possibilities for modification.They bear many similarities to metal complexes of macrocyclic ligands and metalloporphyrins because they possess rigid co-ordination sites surrounding a metal centre [6]. With d 0 electronic configuration of tungsten(VI) species, they do not cause excessive catalytic dismutation of hydrogen peroxide [7].…”