Direct incorporation of a ferric ion in the porphyrinogen core: tetrakis(cyclohexyl)iron porphyrinogen anion with different conformers and its reaction with iodine.
Et(4)N[L' 'Fe(III)].3DCM (1) is directly synthesized by adding ferric chloride into a solution of a lithium salt of tetrakis(cyclohexyl)porphyrinogen (L' '). [L' '](4-) is a good chelating ligand for both Fe(III) and Fe(II) ions. It is an avid proton scavenger but not a reducing agent. 1 showed a magnetic moment (mu(eff)) of 4.3 micro(B) in the solid, which changed to 6.0 micro(B) in solution. This change in spin state is common for all iron porphrinogens. 1 showed polymorphism, and with pyridine in the lattice, it changed to Et(4)N[L' 'Fe(III)].DCM(0.5)Py(1.5) (2), possessing two different conformers. Calculation of these conformers at the density functional theory level showed the relative energies of all d orbital changes in three conformers, highlighting the influence of the disposition of a peripheral ligand. Iodine oxidation of 1 yielded [L' '(DeltaDelta)Fe(II)I][I(3).I(2)(+).I(3)(-)] (3) with the introduction of two C(alpha)-C(alpha) bonds with concomitant reduction of Fe(III) to Fe(II). Its mu(eff) (5.4 mu(B)) in the solid changed to 4.8 micro(B) in solution, suggesting a high spin state (S = 2) for Fe(II).
Bhattacharya
Dibyendu
D
Department of Chemistry, Indian Institute of Technology, Kanpur.
Dey
Soumen
S
Maji
Suman
S
Pal
Kuntal
K
Sarkar
Sabyasachi
S
D000838:Anions / Q000737:chemistry*; D007455:Iodine / Q000737:chemistry*; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011165:Porphyrinogens / Q000737:chemistry* / Q000378:metabolism; D011166:Porphyrins / Q000737:chemistry*
D000838:Anions; D008024:Ligands; D011165:Porphyrinogens; D011166:Porphyrins; C511497:tetrakis(cyclohexyl)iron porphyrinogen; D007455:Iodine; D007501:Iron