Synthesis and characterization of the inclusion compound of a ferrocenyldiimine dioxomolybdenum complex with heptakis-2,3,6-tri- O-methyl-β-cyclodextrin

Abstract

A dioxomolybdenum(VI) complex bearing the diimine ligand N, N′-bis(ferrocenylmethylene)ethylenediamine (FcNN) has been prepared in good yield by the reaction of FcNN with MoO 2Cl 2(THF) 2. One isomeric form was identified by 1H NMR (including NOE experiments), corresponding to the cis, cis geometry with respect to the C N bonds of the free ligand. The polynuclear complex was immobilized in permethylated β-cyclodextrin (TRIMEB) by addition of the guest to a solution of TRIMEB in a mixture of dichloromethane and nitromethane. Removal of the solvent led to the isolation of an inclusion compound with a 2:1 host:guest stoichiometry. For comparison, an inclusion compound containing just the ligand FcNN and TRIMEB was prepared using a similar method. The products were characterized in the solid state by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), FT-IR and 13C CP MAS NMR spectroscopy. UV–Vis measurements were also carried out in solution. Both the complex MoO 2Cl 2(FcNN) and its inclusion compound with TRIMEB catalyze with high selectivity the liquid phase epoxidation of cyclooctene using tert-butyl hydroperoxide (TBHP) as the oxidant. In general, the catalytic behavior of the Mo VI complex was not markedly affected by encapsulation in TRIMEB, although observed activities were slightly lower.