Title

Solution properties of tetrakis-(4-N-methyl)pyridylporphineiron(III)

Document Type

Article

Publication Date

1-1-1977

Abstract

Tetrakis-(4-N-methyl)pyridylporphineiron(III) (FeTMpyP) was synthesized and its aqueous solution properties studied. The visible spectrum of FeTMpyP was found to be dependent on pH and ionic strength. The following equilibria were sufficient to account for the titration data: H O+FeP(H O) {long arrow right, short arrow left}FeP(OH)(H O) +H ;pK =4.7±0.2FeP(OH)(H O) {long arrow right, short arrow left}FeP(OH) +H ; pK =6.5±0.32FeP(OH) {long arrow right, short arrow left}O-(FePOH) +H O; K ≃9×10 M . Magnetic susceptibility measurements and Mössbauer spectroscopy were used to characterize the FeTMpyP species at low and high pH. In the range pH 1-3, monomeric, high-spin, pentacoordinated iron(III) is the primary species. A μ-oxo dimer involving low-spin hexacoordinated iron(III) exists at pH 10-12. The rate of dissociation of the dimer at μ = 0.05 M and t = 25°C was found a two-term rate law: -d[dimer] dt=(k +k′ [H ])[dimer] where k = 0.42 sec and K = 31 M sec . These results are compared with those obtained for the dissociation of dimer of tetraphenylporphinesulfonatoferrate(III), FeTPPS. © 1977. 2 2 2 a1 2 2 a2 2 2 2 D 1 1 1 1 5+ 4+ + 4+ 3+ + 3+ 6+ 5 -1 + -1 -1 -1

Publication Name

Journal of Inorganic and Nuclear Chemistry

Volume Number

39

First Page

1865

Last Page

1870

Issue Number

10

DOI

10.1016/0022-1902(77)80224-8

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