Synthesis and Electrochemical Studies of a Series of Fluorinated Dodecaphenylporphyrins

• Published in: Inorganic chemistry Vol. 38; no. 9; pp. 2188 - 2198
• Main Authors: Kadish, Karl M, Van Caemelbecke, Eric, D'Souza, Francis, Lin, Min, Nurco, Daniel J, Medforth, Craig J, Forsyth, Timothy P, Krattinger, Bénédicte, Smith, Kevin M, Fukuzumi, Shunichi, Nakanishi, Ikuo, Shelnutt, John A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 03.05.1999
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic9811695

Dodecaphenylporphyrins with varying degrees of fluorination of the peripheral phenyl rings (F x DPPs) were synthesized as model compounds for studying electronic effects in nonplanar porphyrins, and detailed electrochemical studies of the chloroiron(III) complexes of these compounds were undertaken. The series of porphyrins, represented as FeDPPCl and as FeF x DPPCl where x = 4, 8 (two isomers), 12, 20, 28, or 36, could be reversibly oxidized by two successive one-electron transfer steps in dichloromethane to give π-cation radicals and π-dications, respectively. All of the compounds investigated could also be reduced by three electrons in benzonitrile or pyridine. In benzonitrile, three reversible reductions were observed for the unfluorinated compound FeDPPCl, whereas the FeF x DPPCl complexes generally exhibited irreversible first and second reductions which were coupled to chemical reactions. The chemical reaction associated with the first reduction involved a loss of the chloride ion after generation of [FeIIF x DPPCl]-. The second chemical reaction involved a conversion between the initially generated Fe(II) porphyrin π-anion radical and the final Fe(I) porphyrin reduction product. In pyridine, three reversible one-electron reductions were observed with the second reduction affording stable Fe(II) porphyrin π-anion radicals for all of the complexes investigated.