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Electrochemistry and Spectroscopy of Sulfate Complexes of (Tetraphenylporphyrinato)manganese
Author(s) -
Lawson Kevin,
Gross Jeff,
Crawford Philip W.
Publication year - 2004
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200490002
Subject(s) - chemistry , dimer , solvent , electrochemistry , manganese , redox , tetraphenylporphyrin , inorganic chemistry , monomer , dissociation (chemistry) , porphyrin , molecule , medicinal chemistry , photochemistry , organic chemistry , electrode , polymer
The electrochemical and spectroscopic properties of [Mn 2 (tpp) 2 (SO 4 )] (H 2 tpp=tetraphenylporphyrin=5,10,15,20‐tetraphenyl‐21 H ,23 H ‐porphine) were studied to characterize the stability of this compound as a function of solvent, redox state, and sulfate concentration. In non‐coordinating solvents such as 1,2‐dichloroethane, the dimer was stable, and two cyclic voltammetric waves were observed in the region for Mn III reduction. These waves correspond to reduction of the dimer to [Mn II (tpp)] and [Mn III (tpp)(OSO 3 )] − , and reduction of [Mn III (tpp)(OSO 3 )] − to [Mn II (tpp)(OSO 3 )] 2− , respectively. In the coordinating solvent DMSO, [Mn 2 (tpp) 2 (SO 4 )] was unstable and dissociated to form [Mn III (tpp)(DMSO) 2 ] + . A single voltammetric wave was observed for Mn III reduction in this solvent, corresponding to formation of [Mn II (tpp)(DMSO)]. In non‐coordinating solvent systems, addition of sulfate (as the bis(triphenylphosphoranylidene)ammonium (PPN + ) salt) resulted in dimer dissociation, yielding [Mn III (tpp)(OSO 3 )] − . Reduction of this monomer produced [Mn II (tpp)(OSO 3 )] 2− . In DMSO, addition of SO $\rm{_{4}^{2-}}$ led to displacement of solvent molecules forming [Mn III (tpp)(OSO 3 )] − . Reduction of this species in DMSO led to [Mn II (tpp)(DMSO)].