Phthalocyanine organometallic complexes

The catalytic activity of phthalocyanine organometallic complexes in hydrocarbon oxidations 281) led to testing such compounds as fuel cell electrocatalysts (282). Phthalocyanine complexes have the structure of Fig. 22 with a multivalent metal, Fe, Co, Ni, or Cu, surrounded by four symmetric nitrogen atoms. These ligands (L) activate the 0-0 bond by forming an adduct with oxygen and thus promote reaction with hydrocarbons... 

Organometallic complexes are known which contain a wide variety of macrocycles closely related to porphyrins corroles, porphycenes, tetraazaporphyrins. phthalocyanines, tetraazaannulenes, and porphyrinogens are the best known examples. Examples containing the first four of these macrocycles are included where there is a useful comparison or contrast with the relevant porphyrin chemistry, but the discussion will not be comprehensive. The four macrocycles are shown in Fig. 2. 

Photo-oxidation reactions, 32 118 Photoreduction, metal oxides, 31 123 Phthalic acid, esterification, 17 340 Phthalocyanines EDA complexes of, 20 328-330 catalytic activity for hydrogen exchange reaction, 20 329,330 electronic configuration of, 20 330 organometallic complexes, 30 276-277 Phyllosilicates, see Layer lattice silicates, catalysts... 

Several metalloporphyrins and phthalocyanines and numerous coordination and organometallic complexes of Rh, Ir, and Pd have also been immobilized directly onto micro- and mesoporous carbon materials, as well as onto CNTs. 

The basic reaction catalyzed by CODH is related to the water gas shift reaction employed industrially to generate H2 by the reaction of CO and H2O. Industrially the process is iron-catalyzed, and numerous organometallic complexes effect the same reaction [133]. Additionally, square-planar Ni(II) complexes electrocatalyze the reduction of CO2 to CO, including [Ni (cyclam)] (cyclam = 1,4,8,11-tetraazacyclotetradecane), nickel-porphyrins and phthalocyanines. The cluster [Fe4S4(SR)4] and certain Fe-porphyrins also catalyze this reaction [124]. 

The catalytic activity of metallic phthalocyanins with respect to biochemical systems is well known. One can interpret the electrocatalytic process as being an oxidation on the surface of the electrode of the cobalt(II) phthalocyanin to cobalt(III) phthalocyanin, followed by a homogeneous oxidation in a solution of thiol according to a redox process which regenerates the cobalt(II) of the organometallic complex. This interpretation confirms the observations of Baldwin and coworkers . 

Unique combinations of properties continue to be discovered in inorganic and organometallic macromolecules and serve to continue a high level of interest with regard to potential applications. Thus, Allcock describes his collaborative work with Shriver (p. 250) that led to ionically conducting polyphosphazene/salt complexes with the highest ambient temperature ionic conductivities known for polymer/salt electrolytes. Electronic conductivity is found via the partial oxidation of unusual phthalocyanine siloxanes (Marks, p. 224) which contain six-coordinate rather than the usual four-coordinate Si. 

Additionally to the theoretical data and synthetic techniques for various metal complexes presented in Chaps. 2-A, we would like to pay special attention to three kinds of coordination compounds (complexes of phthalocyanines, quinones, and radioactive elements), whose syntheses, in our opinion, have been insufficiently generalized in monographs and textbooks on synthetic coordination chemistry. This choice is caused by the facts that phthalocyanines, as n-aromatic macrocyclic compounds, possess unusual thermal stability (nonstandard for organic and organometallic species) the quinone complexes have free-radical properties and coordination and organometallic compounds of radioactive elements are interesting at least for the reasons of necessity of special precautions in their syntheses and applications in the nuclear industry and nuclear medicine. So, this chapter is dedicated to the peculiarities of structure and properties and the main synthetic procedures for the complexes above. 

The present article will focus in particular on structurally characterized complexes and will refer to current trends and potential applications, simultaneously aiming at a coherent picture of the entire family of organometallic lanthanide amides including the inorganic derivatives. The elements Sc, Y, La will be treated as lanthanide elements Ln. Previous reviews cover this subject mostly as an aspect wrapped up under a comprehensive depiction of both metal amides [19] and lanthanide chemistry [20]. Other articles focus on special topics in this field, e.g., inorganic amides [21], silylamides [22], phthalocyanines [23] or porphyrins [24],... 

Besides these classical aromatics and polyaromatic hydrocarbons, other very important classes or arene molecules are porphyrins [60, 61], phthalocyanins [61, 62], porphycens [63], calixarenes [64], resorcarenes [64], cydophanes [47], dendrimers [65], elementa-arenes [66], organometallic arene (hexahapto) [67], benzyne (dihapto), and aryl- and benzyl (monohapto) complexes [68], inorganic pyridine and polypyridine complexes [69], fullerenes [70, 71], and... 

Another advance seems likely through the use of zeolites as enzyme mimics.This centers on the reactions of organometallics with zeolite internal surfaces. The best-known example is the production of a [Co (bipyridyl)(terpyridyl)] + complex inside the main cavity of zeohte Y that can selectively and reversibly absorb oxygen from the air. The catalytic potential of a Co phthalocyanine moiety prepared in the Y cavity has also been demonstrated. 

Additional structural possibilities in Sections 3-5 include complex salts, with 2 3 or 1 2 stoichiometry for phenazine and TCNQ, and many polyiodides. Phenazines thus hardly fit into convenient isostructural families that facilitate systematic investigations. The organic donors related to tetrathiafulvalene (TTF) and macrocyclic organometallic donors involving porphyrins and phthalocyanines have been notably successful in producing isostructural series. The more numerous TCNQ salts and substituted phenazines display instead structural variety, although isostructural pairs undoubtedly exist. Now differences rather than similarities become interesting. 

In addition to the studies on reduction and oxidation of metalloporphyrins, radiolytic methods have been used to investigate reactions of radicals with metalloporphyrins that lead to formation of metal-carbon bonds. Formation of metal-carbon bonds has been implicated in various catalytic reactions and in biological systems. Therefore, numerous studies have been carried out on the formation and decomposition of such bonds involving porphyrin complexes of Pe 38.s3,62,68-70co, ° Rh, and other metals, as well as complexes of related macrocycles, such as Co-phthalocyanine and Co-B,2. Certain oxidation states of transition metal ions react with free radicals by attachment to form organometallic products, some of which are stable but others are short-lived. Pulse radiolysis has been used to investigate the formation and decay of such species. 

The preparations of several organometallic polymers are given here for reference to some more common types of polymers. They are the vinyl type, complex metal phthalocyanines, organotin hydride-olefin condensations, and the poly(metal phosphinates). More detailed reviews on organometallic pol3oners should be consulted for additional information [1,2]. 

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