Iron isocyanides porphyrin

The isocyanide ligand, CNR, is formally isolobal with a carbene ligand. Several studies have investigated iron(Ill) porphyrin isocyanide complexes which have the general formula [FeCPorKCNR) ]. However, these studies have mostly been concerned with spin state and spectroscopic properties rather than chemical transformations and will not be discussed in detail here. Crystallographic details are given for two of the complexes. " ... 

Geminate recombination of iron(II) porphyrin with a number of isocyanides and 1-methylimidazole has been observed by T. G. Traylor, D. Magde, D. Taube and K. Jongeward, J. Amer. Chem. Soc. 109, 5864 (1987). 

Isocyanides have been used to probe the bonding sites in hemoproteins and related compounds (215-219). Additions of CNCH2Ph, PBu , and P(OEt)3 to Fe(II)cap (cap = dianion of capped porphyrine) has produced five-coordinate low-spin iron(II) compounds by jr-acid destabilization of the dz2 orbital of the iron(II) porphyrin (215). 

Nasri H, Ellison MK, Shang M, Schulz CE, Scheldt WR. Variable 7C-bonding in iron(II) porphyrinates with nitrite, CO, and tert-butyl isocyanide Characterization of [Fe(TpivPP)... 

G. Simonneaux and A. Bondon, Isocyanides and Phosphines as Axial Ligands in Heme Proteins and Iron Porphyrin Models, in The Porphyrin Handbook , eds. K. M. Kadish, K. M. Smith, and R. Guilard, Academic Press, New York, 2000, Vol. 5,p. 300. 

Any adequate theoretical treatment must also explain how iron-porphyrin systems can bind not only O2, but also CO, NO, alkyl isocyanides, and alkyl-nitroso moieties. A simple qualitative model presented by Wayland and coworkersconveniently summarizes ligand-binding geometries of cobalt and iron porphyrins. Although a reasonable quantitative theoretical consensus exists for 1 1 cobalt-dioxygen species, the same cannot be said yet for iron-dioxygen systems. 

The valence electrons of iron porphyrins are almost invariably located in the 3d orbitals of the metal, except in the cases of itt-cation radicals of Fe complexes of oxophlorins and reduced hemes bonded to carbon monoxide, isocyanide... 

It has been shown that these carbenes can insert into Fe-Npor bonds to form vinylidine (A(-alkyl-iron porphyrin metallacycle (N-C-C-Fe)) complexes, " which can then go on to form c/s-bridged vinylidines of the porphyrin, with loss of iron. Carbene equivalents of iodosylbenzene can also react with iron porphyrins to give five-membered Fe-O-C-C-N metallocycles. Iron porphyrin carbenes can also react with amines to produce the isocyanide complexes (equation 58) ... 

Isocyanides and Phosphines as Axial Ligands in Heme Proteins and Iron Porphyrin Models Gerard Simonneaux... 

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