| Abstract |
New half-sandwich molybdenum complexes [Mo(CpBZ)Cl-2(O)] (1), [\Mo(CpBZ)(O)(2)\(2)(mu-O)] (5), and [Mo(CpBZ)Cl-2](2) (6) (CpBz = C-5(CH2Ph)(5)), the tungsten derivative [W(CpBZ)Cl(O)(2)] (3), and a high yield synthesis of [Mo(CpBz)Cl(O)(2)] (2) are described. The molecular structures and cyclic voltammetry measurements of 1 and 2 and a comparative study of various molybdenum dioxo complexes as olefin epoxidation catalyst precursors are also presented. The performance of [Mo(CpPr4i)Cl(O)(2)] (9) as cyclooctene epoxidation catalyst using TBHP as oxidant was determined and compared with other [MoCP Cl(O)(2)] complexes (Cp = C,H, (7), C5Me5 (8), CpBz (2)) to assess the activity dependence on the ring substituents. Under the same experimental conditions, bimetallic compounds [\MoCp (O)(2)\(2)(mu-O)] (Cp = CpBz (5), Cp* (10), CpBu3t (11), CpPr4i (12)) have been tested and [CpMoO2](2)O was checked in aqueous solution, with H2O2 and TBHP as oxidant. Finally, [Mo(CpBz)(CO)(3)CH3] (4) was used as a catalyst precursor for cyclooctene epoxidation in the presence of TBHP. The analogy between the behaviors displayed by this complex and complex 2 is discussed. |
