Tetraphenylporphyrin iron chloride

The reaction of p-chlorobenzaldehyde with phenyldiazomethane in the presence of (MeOlsP and catalytic amounts of meso-tetraphenylporphyrin iron chloride (ClFeTPP) resulted in the formation of the corresponding alkenes with an /Z-selectivity of 86 14, but the yield was low (30%). When phenyldiazomethane is generated in situ from the corresponding potassium tosylhydrazone salt, the olefin yield increases to 92% with E/Z-selectivity of 97 3. Thus, high levels of -selectivity are obtained with semistabilized ylides by this method . This process is applied to a wide range of aldehydes and is practical as compared to standard Wittig reaction, and therefore finds applications in industry, o... 

Groves and coworkers [45] were the first to translate these results to a model system. They described the use of iron(III) meso-tetraphenylporphyrin (TPP) chloride in combination with iodosylbenzene for the epoxidation of olefins and hydroxylation of alkanes. Subsequently, chromium [46] and manganese [47] TPP complexes were shown to catalyze oxygen atom transfer from PhIO to an olefin or an alkane. 

Structure 5.17. Tetraphenylporphyrin Iron(III) chloride, with basket-handle of the picket-fence type with secondary amide groups in close vicinity to the porphyrin ring. Reprinted from Structure 16 J. Costamagna, G. Ferraudi, J. Canales and J. Vargas, Carbon dioxide activation by aza-macrocychc complexes, Coordination Chemistry Reviews 148 (1996) 221-248. Copyright 1996, with permission of Elsevier. 

SAMFETs have also been used in chemical sensing. The a-substituted quincpiethiophene SAMFETs were covered with a 10-nm pinhole-riddled iron tetraphenylporphyrin chloride layer, that acts as a receptor to nitric oxide (NO), an important biomarker [74]. The threshold voltage, measured by the FET transfer characteristics with the porphyrin receptor shifts upon increased exposure to NO. Annealing the monolayer FET in vacuum restores the initial FET behavior. Also, in the single monolayer HBC assembled FETs between metallic SWCNT source and drain electrodes increased current levels were measured in /d-Fds and Aj-Fg characteristics (Fig. 9) upon exposure to solutions of the electron acceptor TCNQ [68]. While the mechanism of response is not known, TCNQ has an affinity for coronene, and likely gives rise to charge transfer between electron-deficient TCNQ... 

Iron(III) weso-tetraphenylporphyrin chloride [Fe(TPP)Cl] will induce the autoxidation of cyclohexene at atmospheric pressure and room temperature via a free radical chain process.210 The iron-bridged dimer [Fe(TPP)]2 0 is apparently the catalytic species since it is formed rapidly from Fe(TPP)Cl after the 2-3 hr induction period. In a separate study, cyclohexene hydroperoxide was found to be catalytically decomposed by Fe(TPP)Cl to cyclohexanol, cyclohexanone, and cyclohexene oxide in yields comparable to those obtained in the direct autoxidation of cyclohexene. However, [Fe(TPP)] 20 is not formed in the hydroperoxide reaction. Furthermore, the catalytic decomposition of the hydroperoxide by Fe(TPP)Cl did not initiate the autoxidation of cyclohexene since the autoxidation still had a 2-3 hr induction period. Inhibitors such as 4-tert-butylcatechol quenched the autoxidation but had no effect on the decom-... 

In contrast to the case of inudazoles binding to tetraphenylporphyrins, Wang et have demonstrated that binding of cyanide to high-spin protoporphyrin IX iron(III) chloride in DMSO-c 6 is a two-step process as shown in equations (38) and (39), and whether DMSO acts as a sixth ligand for the mono-cyano complex is not known ... 

The use of a synthetic model system has provided valuable mechanistic insights into the molecular catalytic mechanism of P-450. Groves et al. [34]. were the first to report cytochrome P-450-type activity in a model system comprising iron meso-tetraphenylporphyrin chloride [(TPP)FeCl] and iodosylbenzene (PhIO) as an oxidant which can oxidize the Fe porphyrin directly to [(TPP)Fe =0] + in a shunt pathway. Thus, (TPP)FeCl and other metalloporphyrins can catalyze the monooxygenation of a variety of substrates by PhIO [35-40], hypochlorite salts [41, 42], p-cyano-A, A -dimethylanihne A -oxide [43-46], percarboxylic acids [47-50] and hydroperoxides [51, 52]. Catalytic activity was, however, rapidly reduced because of the destruction of the metalloporphyrin during the catalytic cycle [34-52]. When (TPP)FeCl was immobilized on the surface of silica or silica-alumina, catalytic reactivity and catalytic lifetime both increased significantly [53]. There have been several reports of supported catalysts based on such metalloporphyrins adsorbed or covalently bound to polymers [54-56]. Catalyst lifetime was also significantly improved by use of iron porphyrins such as mew-tetramesitylporphyrin chloride [(TMP)FeCl] and iron mcA o-tetrakis(2,3,4,5,6-pentafluorophenyl)por-phyrin chloride [(TPFPP)FeCl], which resist oxidative destruction, because of steric and electronic effects and thereby act as efficient catalysts of P-450 type reactions [57-65]. 

Other electrocatalyzed reduction reactions were less investigated, but some of them may play an important role in the near future. For example, electrochemical reduction of carbon dioxide, such as that described with iron(lll) 5,10,15,20-tetraphenylporphyrin chloride (FeTPPCl) electrostatically deposited onto carboxylated MWCNTs [205], might become a method of reducing CO2 emission, transforming it into valuable chemicals. 

C5iHftoClFeNeO, Bis(imidazole)-a,/3,7,6-tetraphenylporphinatoiron(111) chloride methanol solvate, 38B, 511 C5 2Cl3FeN60, Nitrosyl-a,, 7,6-tetraphenylporphinato(4-methyl-piperidine) iron (11) chloroform solvate, 43B, 638 C52Cl3MnN60, Nitrosyl-a,, 7,6-tetraphenylporphinato(4-methyl-piper idine )manganese chloroform solvate, 40B, 471 C52H32CI1oNaOeRe2Sb, Bis(tricarbonylrhenium)-M tetraphenylporphyrin hexachloroantimonate bis(dichloromethane) solvate, 43B, 638 C52H3gClCoNg, Chloro-a,, 7,6-tetraphenylporphinato(pyridine)cobalt-(III) benzene solvate, 41B, 574... 

FeHPA = iron substituted Keggin-type heteropolyanion CoTPPC = tetraphenylporphyrin cobalt(III) chloride... 

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