Alcohol-catalyzed photoreduction of iron-porphyrin complexes revealed by resonance raman and absorption spectroscopies

✍ Scribed by T. Ogura; V. Fidler; Y. Ozaki; T. Kitagawa

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 248 KB
• Volume: 169
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(90)87077-5

✦ Synopsis

Photoreduction of Fe"'(OEP) (2-MeIm) (OEP is octaethylporphyrin; Z-MeIm is 2-methylimidazole) was found to be catalyzed by a trace amount of MeOH present m CH& as a stabilizer. The absence of either 2-Melm or MeOH in the CH&l, solution of Fe'n(OEP)X (X is Cl-, Br-or I-) leads to no photoreduction. The presence of MeOH in the Fe'n(OEP) (2-MeIm) solution results in the appearance of a new absorption band at 585 nm, and when Raman scattering was excited at 590 nm, a new Raman band appeared at 524 cm-'. This band exhibited an upshift by 4 cm-' with i4Fe (OEP) (2-MeIm) (CH30H) and a downshift by 12 cm-' with S6Fe(OEP)( 2-Melm)(CD,OD)

and was therefore assigned to the Fe"'-MeOH stretching vibration. The excitation profile of this band gave a peak around 585 nm and accordingly, the new absorption band at 584 nm was assigned to a charge-transfer (CT) band from MeOH to the Fen' ion. It was most unexpected that the photoreduction did not occur upon laser illumination within the CT band