Porphyrins reactions

In a minireview, Marietta94 postulated the series of reactions in Figure 11. The reactions show the details of the iron porphyrin reaction and are concerned with the formation of NO. 

The solid lines in Figs. 25 to 28 are the result of model predictions of metal deposition based on porphyrin reaction pathways. Curves are generated using intrinsic kinetic rate parameters and effective diffusion coefficients for the metal species on the order of 10 6 cm2/sec. These values are similar to diffusion coefficients measured in the independent studies referenced. 

Autoxidadon of Bare ruthenium( II) and osmium(II) porphyrins - A resonance Raman study of the intermediates formed during the reaction of Ru(TPP) (which was obtained according Scheme 1, paths — f, — j, — k) in toluene [258] proved the anticipated [205] reaction scheme of the inner-sphere autoxidation, the first step of which is the formation of a p-peroxobis[porphyrinato-ruthenium(III)] complex which is split into two oxoruthenium (IV) fragments. These species precede the formation of /r-oxobisruthenium(IV) porphyrins (reaction 16) for P = TPP, OEP for P = TMP, a disproportionation (17) is indicated, the resulting Ru(P) itself is further autoxidized. 

By the method of introducing Pt into the DLC, the platinum metal is assumed to be distributed over the carbonaceous material bulk as discrete atoms or clusters [154], Essentially, Pt is not a dopant in the DLC, in the sense that the term is used in semiconductor physics. Nor is the percolation threshold surpassed, since the admixture of Pt (not exceeding 15 at. %) did not affect the a-C H resistivity, as was shown by impedance spectroscopy tests p 105 Q, cm, like that of the undoped DLC (see Table 3). It was thus proposed that the Pt effect is purely catalytic one Pt atoms on the DLC surface are the active sites on which adsorption and/or charge transfer is enhanced [75], (And the contact of the carbon matrix to the Pt clusters is entirely ohmic.) This conclusion was corroborated by the studies of Co tetramethylphenyl-porphyrin reaction kinetics at the DLC Pt electrodes [155] redox reactions involving the Co central ion proceed partly under the adsorption of the porphyrin ring on the electrode. 

Embedded quantum/classical calculations were used to study the epoxidation reaction of styrene catalyzed by Mn-porphyrins. Optimized geometries were obtained for the Mn-porphyrin, reaction intermediates, and transition state structures along the proposed reaction path. A polarizable continuum model (PCM) was used to study solvent effects, with dichloromethane as the solvent. While it has been shown previously that the concerted intermediate between the oxidized porphyrin and the alkene is the lowest energy configuration, a transition state to directly form the concerted intermediate without the prior formation of a radical could not be found. A stepwise mechanism, in which a radical intermediate is formed before the concerted intermediate, is proposed. 

The controlled oxygenation of alkanes, alkenes, and aromatic hydrocarbons is one of the most important technologies for the conversion of crude oil and natural gas to valuable commodity chemicals. Biomimetic studies of metalloporpltyrins have led to important advances in practical catalysis, especially with ruthenium porphyrins. Reaction of wj-CPBA, periodate, or iodosylbenzene with Ru(II)(TMP)(CO) produced RuCVIjfTMPXOjj . Remarkably, Ru(VI)(TMP)(0)2 was found to catalyze the aerobic epoxidation of olefins under mild conditions. Thus, for a number of olefins including cyclooctene, norbomene, cis-, and trans- -methyl styrene 16-45 equivalents of epoxide were... 

Llgand-addltlon reactions of indlumdll) porphyrins. Reactions of (0EP>lnX and InX with R-methylimidazole and pyridine, ... 

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