Metallo-complexes porphyrins molecules

Coordination of small organic molecules by porphyrin complexes gives rise to either five- or six-coordinate ligand—metallo-porphyrin complexes (Eqs. (1) and (2)) ... 

Corrphycenes and their metal complexes undergo four distinct one-electron redox steps, two are reduction steps and two are oxidation steps. A comparison with porphyrins and porphycenes indicates that the first reduction potentials of the free base and of metallo-corrphycenes are between those of porphycene 38, the easiest to reduce molecules, and those of porphyrins 2. The oxidation potentials of corrphycenes and porphyrins, however, are quite similar (00IC2850). The synthesis of hemi-porphycene 70 (Scheme 33) has been achieved (05ACI3047) from corrole 8 (R=C6H5). 

Metal-catalyzed silylene extrusion from hexamethylsilirane 20 was also used to generate transition metal silylenoids [equation (7.2)] 47 In the presence of a metallo-porphyrin, [Os(TTP)]2 (where TTP = the dianion of meso-tetra-p-tolylporphyrin), hexamethylsilirane 20 extruded dimethylsilylene to produce the THF-stabilized osmium silylenoid complex 21. Despite the coordinated THF molecule, crystallographic analysis of the silylosmium complex 21 revealed the sp2 nature of the silicon atom (Os-C-Si bond angles 121° and 117°). Osmium silylenoid 21 was also synthesized from the reaction of [Os(TPP)]2- and dimethyldichlorosilane.47... 

Table XXVI summarizes two different series of wcio-tetraphenylporphyrin derivatives that crystallize in the tetragonal crystal system. The compound, space group, a, c, and unit cell volume are listed for each member. Series a, the four-coordinate species, has H2TPP as the parent compound. The existence of the series is expected and solid solutions of H2TPP and the metallo derivatives listed are readily formed . All members of this series have Ruf core conformations with substantial displacements of the carbon atoms. The second series is a substantial series of five- or six-coordinate complexes of which [Sn(TPP)Cl2] is the prototypical ordered example with symmetry. We first concern ourselves with the subset that have been catalogued as having I4/m as the space group. The phenyl groups of adjacent I-centered molecules make equivalent ligand pockets above and below the porphyrin plane. The pocket size is adequate for small (mono- or diatomic) axial ligands. Most of the species listed in Table XXVI(b) are seen to be five-coordinate hence the complexes display disorder in the crystal and...

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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