Bidentate Lewis base adducts of molybdenum(VI): Ligand impact on catalytic performance and stability

✍ Scribed by Alev Günyar; Fritz E. Kühn

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 533 KB
• Volume: 319
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/j.molcata.2009.12.007

✦ Synopsis

The reaction of solvent substituted [MoO 2 Cl 2 ] (THF) 2 complexes with 1 equiv. of bidentate nitrogen donor ligands leads to complexes of the type [MoO 2 Cl 2 L 2 ] (L 2 = 4,5-diazafluorene-9-one; 1,10-phenanthroline-5,6-dione; 2,2 -biquinoline-4,4 -dicarboxylic acid, diethyl ester; 3,6 -bis-2-pyridyl-pyridazine; 4,4 -diethoxycarbonyl-2,2 -bipyridine) in quantitative yields at room temperature under inert gas atmosphere within a few minutes. The catalytic activity of the [MoO 2 Cl 2 L 2 ] complexes in olefin epoxidation with t-butyl hydroperoxide as oxidizing agent is strongly influenced by the nature of the ligand L and its steric demand. The complexes, with the sole exception of compound 9 [MoO 2 Cl 2 (1,10-phenanthroline-5,6-dione)], are very active and highly selective epoxidation catalysts. The influence of the terminal oxo ligands together with the Lewis base ligands on the Mo center obviously keeps the compounds on a quite stable level of electron density.