Molybdenum(VI) complexes with ligands derived from 5-(2-pyridyl)-2H-tetrazole as catalysts for the epoxidation of olefins

Ionic liquid-stabilized metal oxoclusters: from design to catalytic application

“…Recently, the Lindqvist-type POM [ t Bu-Hptz] 2 [Mo 6 O 19 ] ( t Bu-Hptz = 2- tert -butyl-5-(2-pyridyl)tetrazole) was studied as epoxidation catalysts using readily available and relatively eco-friendly hydroperoxide oxidants (hydrogen peroxide and tert -butyl hydroperoxide). 87 This POM acted as a homogeneous catalyst and could be recycled by employing an IL solvent. It was found that the type of anion of the IL could affect the catalytic performance.…”

Versatile Polyoxometalates of Different Structural Dimensionalities for Liquid Phase Catalytic Oxidation

“…The introduction of alkyl substituent groups in the anilinium cation did not seem to improve the catalytic performance, which may be partly due to differences in catalyst solubility and/or acid-base properties of the anilinium derivatives [31]. The 0-D pyridinium-tetrazole-based polyoxometallates (Hptz) 4 [SiMo 12 O 40 ]•nH 2 O and (tBu-ptz) 2 [Mo 6 O 19 ] performed differently under somewhat comparable reaction conditions, with the latter being less active (88% Ole conversion at 6 h) than the former (97% Ole conversion at 3 h) (entries 8 and 9) [32,33]. Both compounds were less active than 3-5.…”

“…Under somewhat similar reaction conditions to those used for 1-6, the catalyst (Hptz)4[SiMo12O40]•nH2O (ptz = 5-(2-pyridyl)tetrazole) led to 60%/28% LinOx selectivity, 31%/33% LinDiOx selectivity and 9%/40% LinFur selectivity at 87%/100% Lin conversion (6 h/24 h) [32]. On the other hand, only epoxides were formed for a related ionic compound with a substituted ptz organic fragment (tBu-Hptz)2[Mo6O19], which led to 83% LinOx and 17% LinDiOx selectivity at 85% Lin conversion, 24 h/70 °C [33]. For this catalyst, the selectivity towards epoxides remained high at 90 °C (63% and 37% of LinOx and LinDiOx selectivity, respectively, at 100% Lin conversion, 2 h), and no LinFur products were formed [33].…”

“…On the other hand, only epoxides were formed for a related ionic compound with a substituted ptz organic fragment (tBu-Hptz)2[Mo6O19], which led to 83% LinOx and 17% LinDiOx selectivity at 85% Lin conversion, 24 h/70 °C [33]. For this catalyst, the selectivity towards epoxides remained high at 90 °C (63% and 37% of LinOx and LinDiOx selectivity, respectively, at 100% Lin conversion, 2 h), and no LinFur products were formed [33]. 2-pyridyl)tetrazole) led to 60%/28% LinOx selectivity, 31%/33% LinDiOx selectivity and 9%/40% LinFur selectivity at 87%/100% Lin conversion (6 h/24 h) [32].…”