Planar-nonplanar conformational equilibrium in metal derivatives of octaethylporphyrin and meso-nitrooctaethylporphyrin

摘要: The planar and nonplanar conformers of metal derivatives 2,3,7,8,12,13,17,18-octaethylporphyrin (OEP) 5-nitro-2,3,7,8,12,13,17,18-octaethylporphyrin (NO[sub 2]-OEP) are investigated using resonance Raman spectroscopy. structural heterogeneity is assessed by analysis the line shapes structure-sensitive lines. First, in conformation macrocycle has been detected solutions nickel cobalt OEP, that is, both found to coexist at room temperature for these porphyrins but not Cu Zn derivatives. latter metals expand porphyrin core, shifting equilibrium entirely conformer. Second, we find substitution with a single NO[sub 2] group one methine-bridge carbons shifts this planar-nonplanar substantially toward Thus, crowding peripheral substituents contracting core (Ni(II) < Co(II) Cu(II) Zn(II)) displace Finally, frequencies several lines correlate parameters such as size (obtained either from molecular mechanics calculations or X-ray crystallographic studies). 30 refs., 6 figs., 3 tabs.