Influence of structural and electronic properties of organomolybdenum(ii) complexes of the type [CpMo(CO)₃R] and [CpMo(O₂)(O)R] (R = Cl, CH₃, CF₃) on the catalytic olefin epoxidation

Abstract

Six compounds of the type [CpMo(CO)3R] (R = Cl (1), CH3 (2), CF3 (3)) and [CpMo(O2)(O)R] (R = Cl (4), CH3 (5), CF3 (6) (Cp = η5-cyclopentadienyl)) have been synthesised and characterised.

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

“…27 The fluorination of the benzyl moiety does not lead to such a pronounced change of the Mo-R bond distance as observed in the cases of the methyl and the CF 3 derivative (2.234(3) Å). 21 This can be considered as an indication of a more similar reactivity of compounds 1 and 2 with respect to decarbonylation. Furthermore, the bond distances between Mo and the carbonyl ligands are very similar for both compounds (see Fig.…”

Molecular Epoxidation Reactions Catalyzed by Rhenium, Molybdenum, and Iron Complexes

“…A comparison of the crystal structure of the fluorinated compound [CpMo(CO) 3 CF 3 ] to the methyl analogue revealed a partial Mo=CF 2 ···F bond separation . This apparently leads to quite a stable complex, which only undergoes fast decarbonylation in activating solvents (HFIP).…”

Kinetic studies of fluorinated aryl molybdenum(ii) tricarbonyl precursors in epoxidation catalysis

“…Fluorination leads to prolongation of the decarbonylation process in that case. 26 However, the (oxidized) trifluoromethyl Mo(VI) compound is much more active in oxidation catalysis than its methyl derivative, presumably due to its enhanced Lewis acidity. Recently, we were able to demon-strate that insertion of a CH 2 bridge in arylated fluorinated and non-fluorinated molybdenum tricarbonyl complexes helps ease the decarbonylation process.…”

“…4). 14,26,[33][34][35] However, it has to be mentioned that a comparison under these conditions has to be taken with great care, especially since MTO is (considerably) more reactive with hydrogen peroxide as an oxidant. The pre-catalyst to substrate/oxidant ratio was chosen to primarily determine the induction periods.…”