Axial ligation equilibria and dynamics in a redox polyether hybrid: An Fe tetraphenylporphyrin melt

Journal Article · Mon Jan 11 04:00:00 EST 1999 · Inorganic Chemistry

DOI:https://doi.org/10.1021/ic980163c· OSTI ID:316228

Long, J W; Murray, R W ^[1]

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1. Univ. of North Carolina, Chapel Hill, NC (United States). Kenan Labs. of Chemistry

Pyridine axial ligation is investigated in a molten Fe tetraphenylporphyrin fashioned by attaching oligomeric (MW 550) ethylene glycol chains at the p-phenyl ring positions ([Fe(T550PP)Cl]). Dissolution of LiClO{sub 4} electrolyte renders the highly viscous, room-temperature melt (0.40 M in porphyrin sites) modestly ionically conductive, so that microelectrode voltammetry can be employed to follow axial pyridine ligation in a thin film of Fe porphyrin melt resting on the electrode assembly. Introduction of pyridine at the gas/melt interface produces distinctive changes in the microelectrode voltammetry, from which relative populations of chloride and pyridine-coordinated Fe(III) porphyrin can be measured and equilibrium constants for ligation of the Fe(III) and Fe(II) oxidation states estimated. Removal of the pyridine at the porphyrin melt/gas interface causes dissociation of the ligating pyridine in an overall process that has a time constant on the order of 5--10 min at 25 C.

• OSTI ID: 316228
• Journal Information: Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 1 Vol. 38; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
DISSOCIATION
IONIC CONDUCTIVITY
IRON COMPLEXES
MOLECULAR STRUCTURE
PORPHYRINS
PYRIDINE
VALENCE