Synthesis peroxo complexes

M. J. Hinner, M. Grosche, E. Herdtweck, W. R. Thiel, A Merrifield resin functionalized with molybdenum peroxo complexes Synthesis and catalytic properties, Z. Anorg. Allg. Client. 629 (2003) 2251. 

III. SYNTHESIS AND STRUCTURAL CHARACTERIZATION A. Synthesis of Peroxo Complexes... 

One of the most important peroxo complexes synthesized after 1983 is the rhenium species formed from methyltrioxorhenium (MTO) precursor. The synthesis of this complex is achieved in the way indicated in equation 2, by reacting hydrogen peroxide with MTO . The isolated peroxo complex 1 contains in the coordination sphere two /7 -peroxide bridges, a direct metal carbon bond and a molecule of water. The crystal structure of the peroxo rhenium derivative, however, was obtained by substitution of the water molecule with other ligands " more details on this aspect are enclosed in the structural characterization paragraph. 

Synthesis of bimetallic /r-peroxo complexes has been described by Mimoun. In particular, for Co species reaction between a superoxo complex with a reduced metal is a feasible method, for Pt species acid catalyzed hydrolysis of peroxo complex may be used and for Rh or Pd the protocol implies reaction of potassium superoxide with appropriate precursors. 

One of the breakthroughs in the field was reported in 1983 by Mimoun and coworkers . On that occasion they reported the synthesis, characterization and radical reactivity of a class of vanadium peroxo complexes representative of which is the species V0(02)pic (HaOIa, 36. The oxidative ability of this complex has been tested with several aliphatic and aromatic hydrocarbons and the synthetic results obtained can be summarized as in Scheme 20. 

O NMR spectroscopy, 185-6 solid state stractures, 1061-3 synthesis, 1057-9 /r-Peroxo complexes solid state stmctures, 1064-8 synthesis, 1059-61 Peroxodisulfate concentration monitoring, 744 etching formulations, 623 Peroxomonosulfate, concentration monitoring, 744... 

Scheme 8. The synthesis of an acetylacetonate complex of rhodium from the peroxo complex.

As mentioned above, both cis-p-1,2 and p-rj2 172 remain vital candidates as the coordination mode of the peroxide in oxy-Hc and oxy-Tyr. The p-172 172 structure does seem, however, more likely because its particular structure gives a simpler and more straightforward account of all the unusual features of oxy-Hc. In order to distinguish these two possibilities conclusively, the synthesis and characterization of a cis-p-1,2 peroxo complex with a hydroxide bridge presents a serious challenge for inorganic chemists. On the other hand, a single-crystal X-ray analysis for oxy-Hc is currently underway and may provide a definitive answer (234). 

The key to snccessfnl synthesis and isolation of transition metal peroxo complexes depends on the reaction conditions, such as temperatnre and the pH of the medinm. ° With a slight variation of the reaction pH, one can end up with compound of different stoichiometry. In the present case, for the dissolution of niobinm pentoxide, we fonnd a pH of 11 (vide experimental) to be conducive for precipitation and isolation of highly crystalline and stable niobinm peroxo com-ponnd from aqueous solution having a composition [Nb(02)4] T The reaction can be snmmarized as shown in Eqnation 6.1. In most of the peroxo metal complexes reported so far, it has been observed that in order to stabilize a peroxo metal complex in solution and then isolate it in solid state requires the presence of an ancillary ligand. However, in the present case we could isolate the... 

Transition metal peroxo complexes are stoichiometric or catalytic oxidants of organic compounds. Many of them have been structurally characterized Synthesis of several new technetium(VII) nitridoperoxo complexes has been reported recently ... 

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