Anion-radicals of general formula [MTFcP]- (M = 2H, Zn, InCl, and InFc; TFcP2- is a dianion of 5,10,15,20-tetraferrocenylporphyrin) were prepared for the first time in situ by controlled potential reduction of the respective neutral MTFcP complexes in a thin layer spectroelectrochemical cell. UV-vis spectroscopy reveals the formation of a broad NIR band between 827-890 nm and another broad band in the Soret region between 458 and 527 nm. A similar NIR band has previously been assigned to 5,10,15,20-tetra(aryl)porphyrin radical-anions. Additional information on the electronic structure and nature of the vertical excitation energies in the [H2TFcP]- system were obtained by density functional theory (DFT) and time-dependent DFT (TDDFT) methods. DFT calculations predict that the SOMO in the [H 2TFcP]- anion-radical is predominantly localized over the porphyrin core. TDDFT calculations suggest numerous MLCT transitions in addition to the expected π-π* excitations, which play a key role in the formation of unusual UV-vis spectra in the [MTFcP]- anion-radicals.
Bibliographical noteFunding Information:
Generous support from the NSF CHE-1110455, the Minnesota Supercomputing Institute to VN, and the from the Robert A. Welch Foundation (K.M.K, Grant E-680) are greatly appreciated.
- density functional theory
- ferrocene-containing porphyrins
- porphyrin anion-radicals
- time-dependent density functional theory