Iron complexes encapsulated

Iron N,N -bis(2-pyridinecarboxamide) complexes encaged in zeolite Y were used for the partial oxidation of alkanes.99 Epoxidation with manganese N,N -bis(2-pyridinecarboxamide) complexes encapsulated in zeolite Y was also reported.100... 

The most elegant example which demonstrates this aspect of proton transfer equilibrium of heme proteins is the study reported on six coordinated aqua (pyridine) iron(III) porphyrin complexes encapsulated in aqueous micelles [27]. The ferric ion in these complexes is axially co-ordinated to a water and a pyridine molecule, thus having a coordination geometry similar to that of the heme in metmyoglobin. The pH dependence of the absorption spectra of the... 

The HNMR spectra of the diaqua and aqua (hydroxo) hemin complexes encapsulated in micelles have been reported [20] (Fig. 5). The heme methyl resonances in the diaqua species lie in the same region as those of the high-spin bis(dimethyl sulphoxide) iron (III) porphyrin complex [37-39], while those of the aqua (hydroxo) complex appear in a more upheld region. The positions and linewidths of the heme methyl resonances in these complexes are similar to those observed in the aqua and hydroxo hemoproteins [19,40]. The broadness of the ring methyl resonances of both the diaqua and aqua (hydroxo) species in micelles has been ascribed to arise from the hindered rotational tumbling motion of the heme inside the micelles. The spread and linewidth of these resonances are much larger than those of similar high-spin model heme complexes in simple solution [3]. 

Information of the Gif system has been summarized,1055 1123 and new results, including new oxidants such as bis(trimethylsilyl) peroxide,1124 the synergistic oxidation of saturated hydrocarbons and H2S,1125 studies with the Fe3+-picolinate complex encapsulated within zeolites,1126 and the use of Udenfriend s system under Gif conditions1127 were disclosed. Gif-type oxidations were found to be moderately stereoselective.1128 Iron/zinc-containing species involved in Gif-type chemistry were synthesized, and their reactivity and catalytic behavior were studied.1129... 

Selectivity towards pinane hydroperoxide exhibits the highest values until higher conversions when the reaction is carried out in the presence of iron phthalocyanine encapsulated complexes (Figure 5). It even can be as high as 90% at a pinane conversion higher than 80%, when the reaction is carried out at 10 C For CoPc complexes the selectivity towards 2-pinane hydroperoxide exhibits an identical behaviour with the free and the encapsulated complex. 

Iron-phthalocyanine (Fe-Pc) encapsulated in Y and VPI-5 zeolites were used for the oxidation of alkanes or olefins in presence of t-butylhydroperoxide or H2O2 (Fig. 9). Fe-Pc-Y also catalyzed the oxidation of cyclohexane to cyclohexanol and cyclohexanone with t-butylhydroperoxide ( TBHP ). Ruthenium perfluorophthalocyanine complexes encapsulated in NaX ( Ru-Fi6 Pc-X ) were active for the oxidation of cyclohexane with TBHP at room temperature.Manganese(II) bipyridyl complexes in faujasite ( Y ) zeolite are active for the oxidation of cyclohexene to adipic acid in the presence of H2O2 at room temperature. Similarly oxidation reactions have been reported using copper complexes encapsulated in X,Y, and VPI-5 molecular sieves. 

Dinuclear half-sandwich iron complexes are believed to encapsulate each cyclopentadienyl group in a separate cyclodextrin host (Figure 2.3) [479]. 

A quite original approach to selective oxidations using H2O2 is based on polymeric membranes. In one case the polymer (polydimethyl siloxane) is filled with a zeolite which encapsulates an iron complex, i.e. the homogenous catalyst is inunobilized in the membrane. The organic phase and the aqueous phase are fed at opposite sides of the membrane. This system has been used for the oxidation of cyclohexane to cyclohexanol and cyclohexanone, and the products were kept in the organic phase. In addition, Buonomenna used polymeric membranes for the oxidation of benzyl alcohol to benzaldehyde and for the oxidation of cyclohexene, both with H2O2. 

Complexes containing encapsulated metal ions (clathrochelates ) with the formula [M(dioxime)3(BR)2] are known with iron(II) 135, cobalt(ll) 136, cobalt(III) 137, and ruthenium(ll) 138 (Fig. 37) [205-220]. Generally, these macrobicyclic complexes are prepared by template synthesis from a mixture of... 

Compounds 139 are tris(oximehydrazone) derivatives with an iron(ll) ion in the center of the cavity [230]. Compound 140 (Fig. 38) has been known for 30 years [231, 232] and was prepared from a tris(2-aldoximo-6-pyridyl)phos-phine that is capped by a BF unit to encapsulate cobalt(ll), zinc(ll), nickel(ll), and iron(II). All four macrocyclic complexes were characterized later by a comparative X-ray crystallographic study [233-236]. 

In addition, iron(II) complexes of tetraaza macrocyclic ligands 17-20 were encapsulated within the nanopores of zeolite-Y and were used as catalysts for the oxidation of styrene with molecular oxygen under mild conditions (Scheme 9) [57]. 

Meat products have to be stabilised in some cases, as meat lipids contain no natural antioxidants or only traces of tocopherols. Most muscle foods contain, however, an efficient multi-component antioxidant defence system based on enzymes, but the balance changes adversely on storage. The denaturation of muscle proteins is the main cause of the inbalance as iron may be released from its complexes, catalysing the lipid oxidation. Salting contributes to the negative effects of storage, as it enhances oxidation. Using encapsulated salt eliminates the deleterious effect of sodium chloride. 

Aida and Jiang recently reported an iron(II) porphyrin 1-methylimidazole complex covalently encapsulated within a large aryl ethereal dendrimer cage, as... 

Martin et al. have developed a unique series of capped tris(l,2-di-aminoethane) cages which can encapsulate divalent transition metal ions in a near octahedral geometry (28). The iron(II) complex with the ligand (NH2)2sar turns out to be a crossover system in solution [34], but the solid triflate salt is low-spin [43]. This is the only Fe(II) crossover system having 6 identical aliphatic nitrogen donors. 

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