N4 chelates

Electrocatalysis in fuel cells requires as well substances capable of catalyzing the anodic oxidation of fuels as catalysts for the cathodic reduction of oxygen. Several dyestuffs that catalyze oxygen reduction are known, but up to now only one has been described as active in anodic reactions. All these dyestuffs are N4-chelates. 

All the different N4 chelates, however, cannot be used as electrocatalysts in fuel cells as they are oxidized and decomposed under operation conditions in a couple of hours or days. 

Heat treatment of soot—for instance, the acetylene furnace soot Vulcan CX—on which N4 chelates had been dispersed, yields after pyrolytic disintegration of the organic material a soot quality that exhibits even a better 02-reduction activity than the mixture of N4 chelate and soot before pyroly-... 

Pyrolyzed N4 chelates and nitrogen-containing polymers on porous carbons and soots might become an option as electrocatalysts for 02... 

Further, Lippert has reported145 the first N3, N4 chelate of cytosine to a Pt(IV) species. 

Bifunctional N4-Chelates as Comonomers with Other Polymers. 91... 

Physical incorporation of different porphines (9) and also phthalocyanines (2) into polymer matrices were done by pearl polymerisations of glyddyl or 2-hydroxyethyl methacrylate and ethylene dimethacrylate -The amount of inorrporated dtielate is 0,05 to 0.4 wt %(50-70% of the inserted porphyrine). The surface hole is small enough to prevent diffusion of N4-chelates from the interior of the matrix. Also polymers, sudi as polystyrene or polyvinylalcohole, were directly used to incorporate porphyrines or phthalocyanines. ... 

Low molecular N4-chelates may react to polymers where the metal atom is a part of a polymer chain. Generally, ihm w( s for construction of such a polymer are possible (Scheme 5) ... 

The Si, Ge, Sn containing N4-chelates (6J)-(66) react with monovalent alcohols, phenols and carboxylic acids to the corresponding alkoxides, aroxides and carbox-ides Polymers were prepared with analc ous bivalent comonomers. 

A new kind of interesting polymer with an acetylene dianion between the metal atoms of N4-chelates was synttesized Polymeric chelates [Si(C)2Pc] (74) were prepared by reacting Si(Cl)2Pc (63) in THF with bis-bromomagnesiumacetylenes or Si(C2MgBr)2Pc (75) (Eq. 33). 

Table 9. Dark conductivities (compressed powders) of some N4-chelates containing IVa-group elements and oxygen in the chain...

A new concept for metallic conductivity in staggered N4-chelates was introducted by Hanack and Seelig After calculating MO, a tetraazaporphyrine macrocycle with iron as central metal and acetylide ion ( 2 ) as bridging ligand leads to a change in energy band structure. 

N4-chelates covalent bond in another polymer (Chap. 4.2) are interesting either as dye-stuffs with covalent bond or thermally stable compounds. 

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