Organometallic porphyrins

This review essentially comprises a survey of the developments in the organometallic chemistry of porphyrin complexes over the last decade, continuing on from the three reviews published during 1986-1988. Literature since the mid-1980s has been surveyed, and work reported prior to this will be touched on primarily to put the more recent developments into context and will not be described in depth. A new multivolume set encompassing the entire range of porphyrin chemistry has been recently published, and this contains a chapter on organometallic porphyrin chemistry. ... 

The last decade has seen the development of a rich and varied chemistry for or-ganometallic porphyrin complexes of the early transition metals (groups 3 and 4). However, there have been many fewer developments in the organometallic chemistry of the middle transition elements. Despite the paucity of its organometallic porphyrin compounds, molybdenum has played a very important role in... 

Organometallic porphyrin complexes containing the late transition elements (from the nickel, copper, or zinc triads) are exceedingly few. In all of the known examples, either the porphyrin has been modified in some way or the metal is coordinated to fewer than four of the pyrrole nitrogens. For nickel, copper, and zinc the 4-2 oxidation state predominates, and the simple M"(Por) complexes are stable and resist oxidation or modification, thus on valence grounds alone it is easy to understand why there are few organometallic examples. The exceptions, which exist for nickel, palladium, and possibly zinc, are outlined below. Little evidence has been reported for stable organometallic porphyrin complexes of the other late transision elements. 

The complexes discussed in the review generally comprise five- or six-coordinate complexes containing tr-alkyl or aryl ligands. This contrast with transition metal organometallic porphyrin complexes which provide, in addition to cr-bonded... 

Selected data for structurally characterized Group 13 organometallic porphyrin complexes are shown in Table III and representative examples are shown in Fig. 5.26,27,65-67,73,84 Structural data it is difficult to draw conclu-... 

Rg. 5. Molecular structures of selected Group 13 organometallic porphyrin complexes (a) AKOEPXCHs), (b) InfEtioPcXCeHslJ (c) Ga(TAP)(CH=CH2) (TAP = tetraanisylpor-... 

Fig. 7. Molecular structures of selected Group 15 organometallic porphyrin cations and complexes (a) [P(0EP)(C6H5)(0H)]PF6, (b) P(OEP)(C2H5)(=0), 5 [P(OETPP)(CH3)2]PF6, ...

A thorough electrochemical characterization of new metalloporphyrins is nowadays state of the art for the synthetic inorganic chemist. In many of the papers cited in Sects. 3 and 4, a characterization of the new complexes by cyclic voltametry and electrolysis at controlled potential has been done. Thin-layer spectroelectrochemistry is very fruitful [346]. Fortunately, apart from classical articles of Davis et al. [347], Felton et al. [292], Fuhrhop et al. [293], Buchler et al. [190], more recent reviews of Kadish et al. are available which systematically cover the field of general metalloporphyrins [294] or organometallic porphyrin complexes [306]. Therefore, a short, update of these articles will be given in the form of Table 7. For details, the reader is referred to the original literature. 

Fig. 8 Structures of organometallic porphyrin derivatives evaluated as photosensitisers for photodynamic therapy... 

Oxidative addition of various organic substrates RX with Rh porphyrins also yields o-bonded organometallic porphyrin complexes (Eq. 1). 

Organometallic Porphyrin and Corrin Complexes (Written with Giang Vo)... 

The synthesis, chemical properties, and electrochemistry of metallo-porphyrins with metal-metal and metal-carbon bonds have recently been described in two extensive reviews Porphyrins are known to coordinate with most metallic and pseudo-metallic elements and, in theory, synthesis of numerous organometallic porphyrins is possible. However, to date, the synthesis of metal-carbon a-bonded complexes has been limited to metallo-porphyrins with the following central metals Fe, Ru, Co, Rh, Ir, Ti, Al, Ga, In, Tl, Si, Ge, Sn and Zn. These organometallic complexes are of importance as model compounds for understanding the functions and relationships of several biologically important macromolecules, as well as for their chemical reactivity. The insertion of small molecules between the metal ion and the carbon atom of a metalloporphyrin may result in activation of the inserted molecule or may generate new monomeric or polymeric materials. In addition, metal-carbon o-bonded porphyrins can act as precursors in the synthesis of metal-metal bonded derivatives. 

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