Synthesis and Electrochemistry of Tetraphenylporphyrins Containing an Antimony-Carbon sigma-Bond.
The following five antimony(V) tetraphenylporphyrins with sigma-bonded antimony-carbon bonds were synthesized: [(TPP)Sb(CH(3))(2)](+)PF(6)(-), [(TPP)Sb(OCH(3))(OH)](+)PF(6)(-), [(TPP)Sb(CH(3))(OH)](+)ClO(4)(-), [(TPP)Sb(CH(3))(OCH(3))](+)ClO(4)(-), and [(TPP)Sb(CH(3))(F)](+)PF(6)(-). Each compound is stable toward air and moisture and has a high melting point (>250 degrees C). The electrochemistry and spectroelectrochemistry of these sigma-bonded porphyrins were examined in benzonitrile or dichloromethane containing 0.1 M tetrabutylammonium perchlorate as supporting electrolyte and the data compared to those for three previously synthesized OEP derivatives containing similar sigma-bonded and/or anionic axial ligands. Each porphyrin shows two reversible reductions and up to a maximun of one oxidation within the potential window of the solvent. Spectroelectrochemical data indicate formation of a porphyrin pi anion radical upon the first reduction as do ESR spectra of the singly reduced species. However, a small amount of the Sb(III) porphyrin products may be generated via a chemical reaction following electron tranfer. An X-ray crystallographic analysis of [(TPP)Sb(CH(3))(F)](+)PF(6)(-) is also presented: monoclinic, space group C2/c, Z = 8, a = 24.068(5) Å, b = 19.456(4) Å, c = 18.745(3) Å, beta = 94.69(2) degrees, R = 0.056.
Kadish
Karl M.
KM
Department of Chemistry, University of Houston, Houston, Texas 77204-5641, and Department of Chemistry, Faculty of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739, Japan.
Autret
Marie
M
Ou
Zhongping
Z
Akiba Ky
Kin-ya
Masumoto
Shuji
S
Wada
Ryosuke
R
Yamamoto
Yohsuke
Y