Synthesis, characterization, and olefin oksidation applications of mn(II)/CU(II) complexes with heptafluorobutyric acid and bipyridine/phenanthroline ligands

In this study, [Mn(hfba)(H2O)(bpy)2]·hfba (1) and [Cu(hfba)2(phen)(H2O)] (2) complexes were synthesized and their catalytic activities in the oxidation reactions of alkenes were investigated. In both complexes, the common ligand was heptafluorobutyric acid (hfba), and 2-2'-bipyridine (bpy) was used as an auxiliary ligand in the Mn(II) complex and 1,10-phenanthroline (phen) in the Cu(II) complex. The catalytic activities of the synthesized complexes were studied in detail in the oxidation reactions of styrene and cyclohexene. Different parameters such as temperature, solvent, acid/base effect, S/K and O/S mole ratios were investigated in catalytic applications. Studies were carried out in the hexane:water (H:W) two-phase system for both complexes in the oxidation of styrene. After 24 hours of reaction with complex 1 in the presence of tertiarybutylhydroperoxide (TBHP) oxidant at S/K=124, O/S=10 and 80°C, 100% product conversion was obtained and 46.8% benzaldehyde was detected as the main product. With complex 2, 100% product conversion (TOF=25 s-1) was obtained after 4 hours in the H:W/TBHP/80°C system. In the oxidation of cyclohexene, 100% product conversion (TOF=7438.5 s-1) was achieved in 1 minute for complex 1 at ACN/TBHP/80°C, and 100% product conversion was achieved in 3 hours for complex 2 (TOF=33.3 s-1). Ten cycle experiments were performed in the catalyst reuse experiments conducted with complex 2 in the two-phase system.