Mai Y, Balzen AK, Torres RK, Callahan MP, Colson AC. A Modular Strategy for Expanding Electron-Sink Capacity in Noncanonical Cluster Assemblies.
Inorg Chem 2021;
60:17733-17743. [PMID:
34748324 PMCID:
PMC8653162 DOI:
10.1021/acs.inorgchem.1c02373]
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Abstract
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A modular synthetic
strategy is described whereby organometallic
complexes exhibiting considerable electron-sink capacity may be assembled
by using only a few simple molecular components. The Fe2(PPh2)2(CO)5 fragment was selected
as a common electroactive component and was assembled around aromatic
cores bearing one, two, or three isocyanide functional groups, with
the resultant complexes possessing electron-sink capacities of two,
four, and six electrons, respectively. The latter complex is noteworthy
in that its electron-sink capacity was found to rival that of large
multinuclear clusters (e.g., [Ni32C6(CO)36]6– and [Ni38Pt6(CO)48]6–), which are often considered as benchmarks
of electron-sink behavior. Moreover, the modular assembly bearing
three Fe2(PPh2)2(CO)5 fragments
was observed to undergo reduction to a hexaanionic state over a potential
window of about −1.4 to −2.1 V (vs Fc/Fc+), the relatively compressed range being attributed to potential
inversions operative during the addition of the second, fourth, and
sixth electrons. Such complexes may be designated noncanonical
clusters because they exhibit redox properties similar to
those of large multinuclear clusters yet lack the extensive network
of metal–metal bonds and the condensed metallic cores that
typify the latter.
By use of a
modular synthetic strategy and relatively few
molecular components, organometallic complexes exhibiting considerable
electron-sink capacity have been characterized. Complexes bearing
one, two, or three Fe2(PPh2)2(CO)5 fragments bound to aromatic isocyanide cores were found to
possess electron-sink capacities of two, four, and six electrons,
respectively, the latter rivaling the electron-sink capacity of large
polynuclear cluster benchmarks.
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