Metallo-complexes

Korotcenkov, Handbook of Gas Sensor Materials, Integrated Analytical Systems, 

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Janda and Lemer sought to establish that a metal ion or coordination complex need not be included within the hapten used for the induction of abzymes so that they can (i) bind a metallo-complex and thereby (ii) provide a suitable... 

In the last decade, transition metal complexes (e.g. metalloporphyrins) have been used to catalyze epoxidation. These entities can reproduce and mimic all reactions catalyzed by heme-enzymes (cytochromes P-450)54. Synthetic metalloporphyrins are analogous to the prosthetic group of heme-containing enzymes which selectively catalyze various oxidation reactions. The metallo complexes of Fe, Co, Cr, Mn, Al, Zn, Ru, etc. possessing porphyrin ligands have been mostly studied55 -57. Porphyrin ligands (4) are planar and can possess several redox states of the central metallic ions and hence they can exist as oxo metals. 

Activation of an M-CO bond for nucleophilic substitution in anion radical metallo-complexes appears to be quite a general effect (Kaim 1987 Mao et al. 1989,1992 Shut et al. 1995 Klein et al. 1996). Such activation seems to be the basis of metal-cluster catalytic activity. The iron-sulfur cluster (Bu4N)2Fe4S4(SPh)4 deserves to be mentioned here. The cluster is considered as a ferredoxin model (Inoue Nagata 1986) it catalyzes an electron transfer from //-butyl lithium or phenyl lithium to 5-phenyl thiobenzoate or phenylbenzoate (Inoue Nagata 1986). 

Tropocoronands as ligands for mono and binuclear metallo-complexes 86PAC1477. 

In general, electrochemical studies of Cg2 have been devoted to the study of its endohe-dral metallo complexes, in which metal atoms are trapped inside the fullerene cage. Part of the fascination with these molecules stems from two aspects of their electronic structures (1) Unlike noble gas endofullerenes, metallofullerenes are formed from a stable ion-pair association between a fulleride anion of charge n and a cation of charge n, which cannot escape from the anionic cage nor react with other substances outside the... 

In catalysis one may expect the appearance of heterogeneous metallo-complex catalysts containing active centres distributed by the required way . This can result in preparation of highly selective catalysts for structurally sensitive reactions. 

Hydrogenation of O-heterocycles using metallo complex catalysts 85UK289. 

Azetidine hydroxyamino acids (muginic acids), structure, synthesis, and metallo complexes of 82YGK401. 

Porphyrins, phthalocyanins, and their metallo complexes as oxidation catalysts 83UK2O. 

P-Macroheterocycles, formation of metallo complexes from 86MI16. Michaelis-Arbuzov rearrangement of phosphorus heterocycles ... 

Most of the azo dyes destruct because of the low resistance of azo-groups to reducing medium of polymer melt. Azo-dyes metallo-complexes with the composition (1 2), not having free sulfo - and carboxyl groups in the molecule composition are the exception. 

With small (hard) cation Li+ and Na+, this bisalt has a metallo complex structure with 6 thermally stable centres which leads to a carboxylation process. 

Other examples of rate derivation for complex reactions with one route can be constructed in the same fashion as illustrated above for heterogeneous catalytic reactions and for homogeneous metallo-complex and enzymatic catalysis in the two previous chapters. 

Developing an objective assessment of the hazard that copper poses to humans and the environment depends on an intimate understanding of the bioavailability. Bioavailability, which is defined as the extent to which the metal is taken up by the organism upon exposure, depends on the species of the metal or metallo complex and/or how easily it can be transformed to a more or less bioavailable species. The key components of the environmental risk assessment paradigms include problem formulation, analysis (which includes both exposure and effects analysis) and risk characterization (WHO 1998). 

The porphyrin metallo complexes in crude oils, asphaltenes and other natural bitumens are chiefly those of vanadium and nickel although copper, iron and even uranium have been suggested. Recently in a Precambrian shale, porphins were found to chelate with iron, zinc and copper in addition to vanadium and nickel.The origin of these complexes is still uncertain, although several theories have been advanced. Some of these theories could be verified or possibly even disproved if the porphyrin type bound to each metal was known. Furthermore, since these heavy metals are harmful to both health and catalysts, a systematic study of demetallation of metalloporphyrins should prove useful. 

Vitamin B12 was the first metallo complex in living systems to be studied in great depth. 

Enzyme-like reactions have been discussed by Jacobs. Phtalocyanine has been introduced in the cavities of Y zeolite. The resulting catalyst mimics the catalytic activity of cythochrome P-450. Turnover numbers above 10,000 have been reached. The catalyst is active at room temperature, and it is shape selective. It is also thermally and chemically stable. Metallo-complexes incapsulated in zeolites can combine the advantages of homogeneous enzyme reactions and heterogeneous catalysis. 

The silicophosphide P(SiMe3)2 acts as a bridging group in large metallo complexes such as CU96P3o P(SiMe3)2 s (PEt3)i8 [23]. 

From these results, it is clear that chlorophyll adsorbed at an interface can catalyze redox reactions between solutes in the two liquid phases, and these reactions are accompanied by injection of negative charges into the low dielectric membrane interior. Metallo-complexes of porphyrins also have similar catalytic properties at the oil/water interface without illumination [13,14,43]. An advantage of porphyrins as catalysts in such experiments is their chemical stability in different media. 

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