A dinuclear oxo-bridged molybdenum(VI) complex containing a bidentate pyrazolylpyridine ligand: Structure, characterization and catalytic performance for olefin epoxidation

Ionic Liquids Based on Oxidoperoxido-Molybdenum(VI) Complexes with a Chelating Picolinate Ligand for Catalytic Epoxidation

“…However, validation of this hypothesis would require more detailed studies, e.g., computational chemistry. [35,39,[41][42][43][44][45][72][73][74][75][76]. The neutral complex [MoO(O2)2(2,2′-bipy)] led to 28% conversion at 24 h/70 °C, in water (entry 23) [35].…”

“…The neutral complex [MoO(O2)2(2,2′-bipy)] led to 28% conversion at 24 h/70 °C, in water (entry 23) [35]. In the reaction temperature range 25-55 °C, relatively low Cy conversions were reached in the presence of the neutral complexes [MoO(O2)2(L)] with L = chiral oxazoline type ligand (38% conversion at 22 h/25 °C, in toluene) [73], L = ethyl[3-pyridin-2-yl)-1H-pyrazol-1-yl]acetate (22% conversion at 24 h/55 °C, in DCE) [42] or L = 2,2′-bipy (34% conversion at 6 h/55 °C, in TFT) [76] (entries 10,19,22). In the temperature range 55-75 °C, high Cy conversions in the range 90-100% were reached at 6-24 h for neutral complexes [MoO(O2)2(L)] with L = 2-(2-pyridyl)-benzimidazole [72], 2-[3(5)pyrazolyl]pyridine [39,74],2-(1-pentyl-3-pyrazolyl)pyridine [75] (using chlorinated organic solvents, entries 9, 18, 21), L = 4,4′-di-tert-butyl-2,2′-bipyridine [35] (using H2O as solvent, entry 24), or L = bis(pyrazolyl)methane) [45] (without solvent, entry 25).…”

“…Nevertheless, a rough comparison to literature data for complexes consisting of neutral or ionic [MoO(O2)2(L)n] suggests that [H3O][MoO(O2)2(pic)] possesses relatively good activity for Cy epoxidation with TBHP (82%/100% CyO yield at 1 h/3 h reaction, 70 °C). [35,39,[41][42][43][44][45][72][73][74][75][76] [39,74],2-(1-pentyl-3-pyrazolyl)pyridine [75] (using chlorinated organic solvents, entries 9, 18, 21), L = 4,4 -di-tert-butyl-2,2 -bipyridine [35] (using H 2 O as solvent, entry 24), or L = bis(pyrazolyl)methane) [45] (without solvent, entry 25). The anionic complex [MoO(O 2 ) 2 (phox)] -(the cation was not specified) led to 45% conversion at 20 min/80 • C (no solvent) [44].…”

“…Neutral Mimoun type mononuclear complexes are well established catalysts for olefin epoxidation, as highlighted in several reviews [6,7,[26][27][28][29]. These catalytic systems may use eco-friendly oxidants such as hydrogen peroxide [3,4,[30][31][32][33][34][35][36][37][38] and tert-butyl hydroperoxide (TBHP) [8,30,35,[39][40][41][42][43][44][45], and different types of solvents: catalyst/H 2 O 2 systems with organic solvents [3,4,[30][31][32][33][34], water [35], ionic liquids [36,37,46] or without solvent [38]; and catalyst/TBHP systems with an organic solvent [8,30,[39][40][41][47][48][49][50]…”

“…Comparison of the catalytic results of the compounds prepared to literature data for complexes consisting of neutral or ionic [MoO(O 2 ) 2 (L) n ] tested for the model reaction of Cy/TBHP[35,39,[41][42][43][44][45][72][73][74][75][76].…”