Synthesis and Catalytic Applications of ansa Compounds with Cycloalkyl Moieties as Bridging Units: A Comparative Study

Abstract

Abstract:The molybdenum and tungsten compounds (MoA C H T U N G T R E N N U N G {h-CH}(CO) 3 ) (2a, 3a n = 3; 2b, 3b n = 4; 2c, 3c n = 5; 2d, 3d n = 6) were synthesized by reacting the spiro-bicyclic compounds 1a-d with theNMR spectroscopy, as well as X-ray diffraction studies, confirm the formation of an intramolecular ansa bridge. The complexes display a good stability in the solid state (stable up to 180 8C under air, as determined by thermogravimetric studies) and are highly active catalysts at room temperature (molybdenum compounds) or above (tungsten compounds) in olefin epoxidation. In the case of cyclooctene as substrate, TOFs up to ca. 11800 h À1 are obtained. Moreover, most of the catalysts described here display a high selectivity in the epoxidation of cis-and transstilbene. In addition, the novel complexes were compared with previously synthesized related compounds, at least matching their catalytic performances.

Aryl-substituted organomolybdenum(ii) complexes as olefin epoxidation catalysts

“…Compound 1: crystal data and details of the structure determination: formula: C 15 Compound 2: crystal data and details of the structure determination: formula: C 15 H 7 F 5 MoO 3 , M r = 426.15; crystal color and shape: yellow fragment, crystal dimensions = 0.09 × 0.14 × 0.36 mm; crystal system: monoclinic; space group P2 1 / n (no. 14); a = 8.1106 (2) …”

Synthesis and characterization of novel cyclopentadienyl molybdenum imidazo[1,5-a]pyridine-3-ylidene complexes and their application in olefin epoxidation catalysis

“…Of these, the ansa-bridged cyclopentadienyl Mo complex [{g 5 -C 5 H 4 [CH(CH 2 ) 3 ]-g 1 -CH}Mo(CO) 3 ] [16] shows the highest TOF in ciscyclooctene epoxidation, namely 11,800 h À1 in organic solvents [17] and TOFs up to 44,000 h À1 in room temperature ionic liquids (RTILs) [18].…”

MoO 2 (acac) 2 anchored on organic copolymer-inorganic hybrid zirconium phosphonate-phosphate functionalized by pyridines as highly efficient, reusable catalysts for alkene epoxidation

“…Molybdenum-based catalysts have been widely used in this reaction [13][14][15][16][17][18][19][20][21][22][23][24]. Molybdenum-based catalysts used in homogeneous phase had shown remarkable catalytic activity and efficient use of oxidant in olefin epoxidation processes but display industrial problems associated with corrosion and deposition of the catalyst as well as difficulty in catalyst recovery [25][26][27][28][29][30].…”