Cobaltocene-oxygen complex

Further experiments (159), including gas titrations, reactivity studies, and spectroscopic evidence, led to the formulation of the intermediate, earlier postulated (158) to be an oxygenated cobaltocene adduct, as the organic peroxide structure 63, in which the dioxygen bridge once again links the cyclopentadiene ligands in an exo fashion. This complex... 

The diborylated cobaltocenium species [(CpBR2)2Co] + (R = t-Pr) is an interesting example that illustrates the different binding modes encountered for bifunctional Lewis acids.With hydroxy counterions, an oxygen-bridged complex (178), which represents an inverse chelate structure, was confirmed in the solid state and in solution (R = t-Pr, F). Salt-like structures on the other hand were observed with PFe as the counterion and a zwitterionic 1 1 complex (179) formed upon reaction of the diborylated cobaltocene with hexachloroethane. Low-temperature NMR studies show that the chloride rapidly exchanges position between the two Lewis-acidic boron centers. 

The mechanisms of the oxidation of phosphines and arsines by chromium(VI) have been examined both in solution and on a diatomite support. Kinetic parameters are presented for both supported and solution reactions. A ruthenium complex of 1,4,8,1 l-tetramethyl-l,4,8,ll-tetraazacyclotetradecane has been utilized to oxidize triphenylphosphine in acetonitrile. Although a limited temperature range was utilized, a AH value of 8.7 0.8 kcal mor and a A5 value of -20 2 cal K mor were calculated. The secondary phosphine oxides, HP(0)R (R = n-butyl, isobutyl, cyclohexyl) and 9H-9-phosphabicyclononane-9-oxide, react with cobaltocene to yield dihydrogen and cobalt(I) compounds. With the less bulky phosphorus ligands at elevated temperatures trinuclear cobalt(III, II) complexes may be obtained. Arsenious acid may be utilized to catalyze the oxygen atom... 

Cobaltocene reacts with oxygen and oxidants, tetrafluoroethylene and halides. The reaction of cobaltocene with dihalogenomethanes gives ring extension. For instance, borabenzene complexes are accessible in this way by reaction with alkyldi-halogenoboranes. 

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