At the Borderline between Metal-Metal Mixed Valency and a Radical Bridge Situation: Four Charge States of a Diruthenium Complex with a Redox-Active Bis( mer-tridentate) Ligand
The complex ions [L Ru(μ,η :η -BL)RuL ] (1 , L = 4,4',4″-tri- tert-butyl-2,6,2',6″-terpyridine and H BL = 1,2-bis(salicyloyl)hydrazide(2-)) were isolated with PF or ClO counterions ( n = 1) and as bis(hexafluorophosphate) ( n = 2). Structural, electrochemical, and spectroscopic characteriz...
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| Published in: | Inorganic chemistry Vol. 57; no. 7; p. 3983 |
|---|---|
| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
United States
02.04.2018
|
| ISSN: | 1520-510X, 1520-510X |
| Online Access: | Get more information |
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| Summary: | The complex ions [L
Ru(μ,η
:η
-BL)RuL
]
(1
, L
= 4,4',4″-tri- tert-butyl-2,6,2',6″-terpyridine and H
BL
= 1,2-bis(salicyloyl)hydrazide(2-)) were isolated with PF
or ClO
counterions ( n = 1) and as bis(hexafluorophosphate) ( n = 2). Structural, electrochemical, and spectroscopic characterization reveals the monocation as intermediate ( K
= 10
) in the three-step reversible redox system 1
. The 1
ion has the molecule-bridged (Ru- - -Ru 4.727 Å) ruthenium centers involved in five- and six-membered chelate rings, and it exhibits long-wavelength absorptions at λ
2240, 1660, and 1530 nm (ε
= 1000, 3000, and 8000 M
cm
, respectively), which would be compatible with a Ru
Ru
mixed-valent situation or with a coordinated radical ion bridge. In fact, EPR and DFT analysis of 1
reveals that the spin is equally distributed over the ligand bridge and over both metals. The oxidized paramagnetic ions 1
and 1
have been studied by
H NMR and EPR and by TD-DFT supported UV-vis-NIR and MIR (mid-IR) spectroelectrochemistry. The capacity of various kinds of bis( mer-tridentate) bridging ligands (π donors or π acceptors, cyclometalated or noncyclometalated) for mediating metal-metal interactions is discussed. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 1520-510X 1520-510X |
| DOI: | 10.1021/acs.inorgchem.8b00173 |