Prophyrin Complexes

We first give an overview of the general features of these various compounds and the means by which they have been characterized (Sect. 4.1). The individual classes of compounds are then described, beginning with the dionedioximates (Sect. 4.2), followed by the most important class, the prophyrinic complexes (Sect. 4.3), and then, briefly, by the dithiolates and porphyrin-like analogues (Sect. 4.4). 

The determination of prophyrin complexes of Ni, V, and Fe is important due to their geochemical importance as well as their poisonous effect on catalysts during refinery operations. Capillary gas chromatography might be successfully used for their determination. 

C. J. Carrano and M. Tsutsui. Unusual metalloporphyrins Synthesis and properties of a dimetallic boron prophyrin complex. /. Coordination Chem., 1977, 7, 125. 

The metal ion, e.g. Fe or Co, when in its lower oxidation state can share electron charge with the oxygen molecule adduct. Several iron and cobalt prophyrin derivatives and cobalt-Schiff bases show the necessary reversibility and rates for successful application [e.g. 23]. a, a, a", a" -weso-tetrakis[(o-piralamidophenyl)-po phinato] Co (II) has been complexed with 1-methylimidazole to make a complex (CoPIm) which, when mixed with polybutyl methacrylate gave oxygen permeabilities on the order of 10-9 sec-cm/(cm2-s-cmHg) with a selectivity of about 5 over nitrogen [23]. 

Sulfite reductase catalyzes the six-electron reduction by NADPH of sol" to and NO2 to NH3. In E. coli this enzyme is a complex structure with subunit composition 0 8)84 (Siegel et al, 1982). The enzyme active site is on the /3 subunit, which contains both a 4Fe 4S cluster and a siroheme prophyrin. Substrates and ligands have been found to bind to the siroheme. The a subunit binds NADPH and serves to shuttle electrons to the active site through bound FAD and FMN groups. Isolated )8 subunits can catalyze sulfite reduction in the presence of a suitable electron donor. 

X0 complexes, 37 272-282 phosphine complexes, 37 271-274 phosphite complexes, 37 272, 274 prophyrin and phthalocyanine complexes, 37 251-253 pyridine oxide complexes, 37 284 2-pyridinethiolato, 2-pyrimidinethiolato, and thiopyrine complexes, 37 295-296... 

Scheme 1. Reaction paths a-o of ruthenium (II) and osmium (II) prophyrins starting from carbonylmetal (II) complexes MCO (P) L (M = Ru, Os). For reaction conditions and references, see Table 4...

Complexes based on prophyrins as artificial enzymes 93CRV2295. 

The therapeutical use of CujZujSuperoxide dismutase as scavenger for the potentially toxic superoxide anion is limited on very special events The half-time of circulation in the organism is very short and it is unable to pass cellular membranes. As a consequence it was attempted to search for lipophilic substances, able to catalyze the dismutation of superoxide, but resistant to biological chelators. One approach was the use of different metalloporphyrins. Some iron and manganese prophyrins catalyze the disnxutation of superoxide with about 3 % efficiency of native CUjZnj-SOD 268) Apart from copper porphyrins, which are inactive as superoxide dismutases, no copper complexes have been described which are at the same time scavengers of superoxide and stable to proteins or EDTA. 

Chromoproteins proteins which contain a colored prosthetic group bound covalently or noncova-lently. The group includes heme proteins and iron prophyrin enzymes, flavoproteins, chlorophyll-protein complexes, and the non-porphyrin iron and copper proteins in the blood of vertebrates (e. g. transferrin and ceruloplasmin), and invertebrates (e.g. hemery-thrin and hemocyanin). 

Direct aerial oxidation of cobalt(ii) in the presence of acetone, acetonitrile, and malononitrile has been used for the first time in the porphjrrin series to generate organocobalt(m) porphyrin derivatives. The acetonyl species [Co-(TPP)CHaCOCH3] was characterized by an JlT-ray crystal structure and found to have (Co—C)=2.028 A. The complexes are stable in solution and apparently fairly stable to light. A further novel alkylation of prophyrins involves electro-... 

---