Characterization of a delocalized mixed-valence bis-macrocyclic diiron compound

Journal Article · Wed Apr 27 00:00:00 EDT 1994 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00087a006· OSTI ID:6835307

Spreer, L O; Li, A; Allan, C B ^[1]; MacQueen, B; Otvos, J W; Calvin, M ^[2]; Frankel, R B ^[3]; Papaefthymiou, G C ^[4]

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1. Univ. of Pacific, Stockton, CA (United States)
2. Lawrence Berkeley Lab., CA (United States)
3. California Polytechnic State Univ., San Luis Obispo, CA (United States)
4. Massachusetts Institute of Technology, Cambridge, MA (United States)

A mixed-valence Fe[sup II]/Fe[sup III] compounds has been obtained by electrochemical oxidation of a bis-macrocyclic Fe[sup II]/Fe[sup III] complex. The binucleating ligand provides a delocalized [pi] system that facilitates electronic interaction between the metals. The Moessbauer spectrum of the mixed-valence compound consists of a single quadrupole-split doublet down to 4 K which establishes the equivalency of the two iron atoms. The cyclic voltammogram of the Fe[sup II]/Fe[sup III] species in rigorously dried acetonitrile shows two reversible oxidations with [Delta]E[sub 1/2] = 500 mV. This corresponds to a comproportionation constant for the mixed-valence compound of 10[sup 11]. This large value also indicates the mixed-valence species is valence-averaged class III and is stabilized by delocalization. The mixed-valence compound has an intense near-infrared band ([lambda][sub max] = 940 nm, [epsilon] = 27 000 M[sup [minus]1] cm[sup [minus]1]). Analysis of this band using Hush's equations for an intervalence transition also indicates the system is delocalized.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6835307
• Journal Information: Inorganic Chemistry; (United States), Vol. 33:9; ISSN 0020-1669
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IRON COMPLEXES
ELECTRONIC STRUCTURE
ABSORPTION SPECTROSCOPY
ELECTROCHEMISTRY
MATHEMATICAL MODELS
MOESSBAUER EFFECT
VALENCE
VOLTAMETRY
CHEMISTRY
COMPLEXES
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400400 - Electrochemistry