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1970074 
Journal Article 
CHARACTERIZATION WITH MO-95, O-17, H-1-NMR AND EPR OF ALKYLPEROXO, ALKOXO, PEROXO AND DIOLO MOLYBDENUM(VI) COMPLEXES FORMED IN THE COURSE OF CATALYTIC EPOXIDATION OF CYCLOHEXENE WITH ORGANIC HYDROPEROXIDES 
Talsi, EP; Klimov, OV; Zamaraev, KI 
1993 
83 
3 
329-346 
WOS:A1993LQ32700007 
Using Mo-95, H-1, O-17 NMR and EPR, we have characterized molybdenum(VI) complexes formed in the course of catalytic epoxidation of cyclohexene with tert-butyl and cumene hydroperoxides. Dioxobis (acetylacetonato) molybdenum (VI) and hexacarbonyl molybdenum (0) were used as starting materials for the catalysts. Six new molybdenum (VI) complexes (I-VI) were detected. Complexes I, II and III are formed when ROOH is added to solutions Of MoO2 (acac) 2 in pure benzene. In benzene:cyclohexene:hydroperoxide mixtures complexes I-III are observed only at the initial stage of the epoxidation process.Then they are gradually replaced by complexes IV-VI that drive the catalytic cycle of epoxidation. NMR spectra of complexes IV-VI are the same, irrespective of whether MoO2 (acac)2 or Mo(CO)6 have been used as the starting material for the catalysts. On the basis of the Mo-95, H-1, O-17 NMR, EPR spectra and reactivity studies, the following compositions for I-VI are suggested: I is the alkylperoxo complex MoO2 (OOR)2, II the alkoxo complex MoO2(OR)2, III the monoperoxo complex MoO (O2) (acac) 2, IV and V are two types Of MoO2 (1,2-diolo), complexes (where 1,2-diolo is trans-cyclohexane-1,2-diol), and VI the alkylperoxo complex MoO2(1,2-diolo) (OOR). The latter complex serves as the active particle of epoxidation. 
ALKYLPEROXO COMPLEXES; EPOXIDATION; EPR; H-1 NMR; HYDROPEROXIDES; MOLYBDENUM; MO-95 NMR; O-17 NMR