Crystal structure and resonance Raman spectra of chloro[tetra(p-methoxyphenyl)porphyrinatoiron(III)]

Raman spectroscopy has been used to provide solution structural information on metalloporphyrins for many years. Recent solid state work [1] found that the totally symmetric ν4 high spin iron(III) oxidation state marker band in malaria pigment is enhanced when using a 780-nm excitation line. Closely related 5 coordinate high spin Fe3+ heme compounds sometimes show the enhancement and sometimes do not. The single crystal X-ray structure of chloro[tetra(p-methoxyphenyl)porphyrinato iron(III)], Fe(TMPP)Cl, recrystallized by vapor diffusion of diethyl ether into a dichloromethane solution was determined. The average Fe-N distance is 2.058(7) Å; and the geometry is entirely typical for a high spin five coordinate iron(III) porphyrin. The corresponding resonance Raman spectrum shows enhancement of the ν4 band with 780-nm excitation. The current work presents comparison of supramolecular features of closely related metalloporphyrin complexes that exhibit the ν4 enhancement and those that do not in exhibit attempt to demonstrate correlation of structural features and then enfluences on ν4 band. [FeCl(C48H36N4O4)], Mr = 824.11, orthorhombic, Pbca, a =22.5275 (7), b = 15.0824 (6), c = 23.1602 (9) Ǻ, V = 7869.1(5) Ǻ3, Z= 8, DCalc = 1.391 Mg m-3, Mo Kα, μ = 0.503 mm-1, F(000) = 3416, T= 123 K, R = 0.153 for 6887 unique observed reflections.