Structure-sensitive resonance Raman bands of capped tetraphenylporphyrinatoiron complexes.

Resonance Raman spectra have been determined for the capped tetraphenylporphyrinatoiron complexes and their base adducts. The five-coordinate mono-base complexes of these porphyrin complexes display Raman spectra that are nearly identical to those previously determined for five-coordinate iron(II) tetraphenylporphyrin complexes in the marker regions around 1540, 1345, and 370 cm(-1). A similar correspondence is found between Raman bands of iron(II) complexes of the capped complexes and those of tetraphenylporphyrin. By contrast, the unusual pseudo-six-coordinate iron(II) complexes more closely resemble high-spin five-coordinate systems in the 1540 and 1345 cm(-1) regions, but in the 380 cm(-1) region the resemblance is closer to the low-spin six-coordinate tetraphenylporphyrin complexes. These results provide spectroscopic confirmation for the unique nature of these pseudo-six-coordinate complexes.