Electronic Coupling and Electron Transfer between Two Mo2 Units through meta- and para-Phenylene Bridges.
Chemistry
; 25(15): 3930-3938, 2019 Mar 12.
Article
em En
| MEDLINE
| ID: mdl-30561861
ABSTRACT
A series of three Mo2 dimers bridged by a meta-phenylene group has been studied in terms of electronic coupling (EC) and electron transfer (ET) in comparison with the para isomers. Optical analyses on the mixed-valence complexes indicate that by replacing a para-phenylene bridge with a meta one, the EC between the two Mo2 centers is dramatically weakened; consequently, the ET rates (ket ) are lowered by two to three orders of magnitude. In the para series, the EC parameters (Hab ) and ET rates (ket ) are greatly affected by O/S atomic alternation of the bridging ligand. However, for the meta analogues, similar EC and ET parameters are obtained, that is, Hab =300-400â
cm-1 and ket ≈109 â
s-1 . These results suggest that through-σ-bond and/or through-space coupling channels become operative as the π conjugation is disabled. DFT calculations reveal that destructive quantum interference features seen for the meta series arise from the cancellation of two π-conjugated coupling pathways.
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MEDLINE
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En
Ano de publicação:
2019
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Article