Synthesis, structures, and reactivity of isomers of [RuCp(1,4-(Me 2 N) 2 C 6 H 4 )] 2
[RuCp*(1,3,5-R 3 C 6 H 3 )] 2 {Cp* = η 5 -pentamethylcyclopentadienyl, R = Me, Et} have previously been found to be moderately air stable, yet highly reducing, with estimated D + /0.5D 2 (where D 2 and D + represent the dimer and the corresponding monomeric cation, respectively) redox potentials of...
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Published in | Dalton transactions : an international journal of inorganic chemistry Vol. 50; no. 37; pp. 13020 - 13030 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Cambridge
Royal Society of Chemistry
07.10.2021
|
Subjects | |
Online Access | Get full text |
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Summary: | [RuCp*(1,3,5-R
3
C
6
H
3
)]
2
{Cp* = η
5
-pentamethylcyclopentadienyl, R = Me, Et} have previously been found to be moderately air stable, yet highly reducing, with estimated D
+
/0.5D
2
(where D
2
and D
+
represent the dimer and the corresponding monomeric cation, respectively) redox potentials of
ca.
−2.0 V
vs.
FeCp
2
+/0
. These properties have led to their use as n-dopants for organic semiconductors. Use of arenes substituted with π-electron donors is anticipated to lead to even more strongly reducing dimers. [RuCp*(1-(Me
2
N)-3,5-Me
2
C
6
H
3
)]
+
PF
6
−
and [RuCp*(1,4-(Me
2
N)
2
C
6
H
4
)]
+
PF
6
−
have been synthesized and electrochemically and crystallographically characterized; both exhibit D
+
/D potentials slightly more cathodic than [RuCp*(1,3,5-R
3
C
6
H
3
)]
+
. Reduction of [RuCp*(1,4-(Me
2
N)
2
C
6
H
4
)]
+
PF
6
−
using silica-supported sodium–potassium alloy leads to a mixture of isomers of [RuCp*(1,4-(Me
2
N)
2
C
6
H
4
)]
2
, two of which have been crystallographically characterized. One of these isomers has a similar molecular structure to [RuCp*(1,3,5-Et
3
C
6
H
3
)]
2
; the central C–C bond is
exo
,
exo
,
i.e.
, on the opposite face of both six-membered rings from the metals. A D
+
/0.5D
2
potential of −2.4 V is estimated for this
exo
,
exo
dimer, more reducing than that of [RuCp*(1,3,5-R
3
C
6
H
3
)]
2
(−2.0 V). This isomer reacts much more rapidly with both air and electron acceptors than [RuCp*(1,3,5-R
3
C
6
H
3
)]
2
due to a much more cathodic D
2
˙
+
/D
2
potential. The other isomer to be crystallographically characterized, along with a third isomer, are both dimerized in an
exo
,
endo
fashion, representing the first examples of such dimers. Density functional theory calculations and reactivity studies indicate that the central bonds of these two isomers are weaker than those of the
exo
,
exo
isomer, or of [RuCp*(1,3,5-R
3
C
6
H
3
)]
2
, leading to estimated D
+
/0.5D
2
potentials of −2.5 and −2.6 V
vs.
FeCp
2
+/0
. At the same time the D
2
˙
+
/D
2
potentials for the
exo
,
endo
dimers are anodically shifted relative to those of [RuCp*(1,3,5-R
3
C
6
H
3
)]
2
, resulting in much greater air stability than for the
exo
,
exo
isomer. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/d1dt02155a |