Transition metal porphyrin complexes

[2][3] They are catalysts and exhibit rich optical properties, although these complexes remain mainly of academic interest.

The periphery of the porphyrins, consisting of sp2-hybridized carbons, generally display only small deviations from planarity.

[7] Large metals such as zirconium, tantalum, and molybdenum tend to bind two porphyrin ligands.

These syntheses require somewhat forcing conditions,[9] consistent with the tight fit of the metal in the N42- "pocket."

Complexes of the type Fe(P)Cl are square-pyramidal and high spin with idealized C4v symmetry.

[12] Typical stoichiometries of ferrous porphyrins are Fe(P)L2 where L is a neutral ligand such as pyridine and imidazole.

[15][16] Metalloporphyrins are also studied as catalysts for water splitting, with the purpose of generating molecular hydrogen and oxygen for fuel cells.

[20] A guest-free base porphyrin is bound to the center by coordination with its four-pyridine substituents.

A picket-fence porphyrin complex of Fe, with axial coordination sites occupied by methylimidazole (green) and dioxygen (R = amide groups). [ 1 ]
Side view of Fe(OEP)CS (ethyl groups removed for clarity), showing the highly planar nature of the porphyrin ring. In this case, Fe is elevated by 0.23 Å above the N4 plane. In the related Fe(OEP)CS(pyridine) complex, the FeN4 groups are coplanar. [ 4 ]
Chemical structure of the bis(porphyrin) complex Zr(OEP) 2 . [ 5 ]
Protoporphyrin IX is the precursor to heme and closely related to chlorophyll .
On a gold surface porphyrin derivative molecules (a) form chains and clusters (b). Each cluster in (c,d) contains 4 or 5 molecules in the core and 8 or 10 molecules in the outer shells ( STM images). [ 19 ]
An example of porphyrins involved in host–guest chemistry . Here, a four-porphyrin–zinc complex hosts a porphyrin guest. [ 20 ]