Synthesis, Characterization and Electrochemical Properties of Stable Osmabenzenes Containing PPh 3 Substituents
Abstract Progress in osmabenzene chemistry : The new stable osmabenzene phosphonium salts can be easily obtained from the reaction of [OsX 2 (PPh 3 ) 3 ] with HCCCH(OH)CCH, which constitutes a valuable addition to previous metallabenzene synthetic methodologies (see scheme). The redox behavior of...
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| Published in | Chemistry : a European journal Vol. 15; no. 14; pp. 3546 - 3559 |
|---|---|
| Main Authors | , , , , , , , |
| Format | Journal Article |
| Language | English |
| Published |
23.03.2009
|
| Online Access | Get full text |
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| Summary: | Abstract
Progress in osmabenzene chemistry
: The new stable osmabenzene phosphonium salts can be easily obtained from the reaction of [OsX
2
(PPh
3
)
3
] with HCCCH(OH)CCH, which constitutes a valuable addition to previous metallabenzene synthetic methodologies (see scheme). The redox behavior of several osmabenzenes with different co‐ligands has been investigated.
magnified image
Treatment of [OsCl
2
(PPh
3
)
3
] with HCCCH(OH)CCH/PPh
3
produces the osmabenzene [Os{CHC(PPh
3
)CHC(PPh
3
)CH}Cl
2
(PPh
3
)
2
][OH] (
2
), which is air stable in both solution and solid state. The key intermediate of the one‐pot reaction, [OsCl
2
{CHC(PPh
3
)CH(OH)CCH}(PPh
3
)
2
] (
3
), and the related complex [Os(NCS)
2
{CHC(PPh
3
)CH(OH)CCH}(PPh
3
)
2
] (
7
) have been isolated and characterized, further supporting the proposed mechanisms for the reaction. Reactions of
3
with PPh
3
, NaI, and NaSCN give osmabenzene
2
, iodo‐substituted osmabenzene [Os{CHC(PPh
3
)CHCICH}I
2
(PPh
3
)
2
] (
4
), and thiocyanato‐substituted osmabenzene [Os{CHC(PPh
3
)CHC(SCN)CH}(NCS)
2
(PPh
3
)
2
] (
5
) respectively. Similarly, reaction of [OsBr
2
(PPh
3
)
3
] with HCCCH(OH)C CH in THF produces [OsBr
2
{CHC(PPh
3
)CH(OH)CCH}(PPh
3
)
2
] (
9
), which reacts with PPh
3
/Bu
4
NBr to give osmabenzene [Os{CHC(PPh
3
)CHC(PPh
3
)CH}Br
2
(PPh
3
)
2
]Br (
10
). Ligand substitution reactions of
2
produce a series of new stable osmabenzenes
11
–
17
. An electrochemical study shows that osmabenzenes
2
,
12
, and
14
–
17
have interesting different electrochemical properties due to the different co‐ligand. The oxidation potentials of complexes
2
,
12
,
16
, and
17
with Cl, NCS, and N(CN)
2
ligands gradually positively shift in the sequence of Cl<NCS<N(CN)
2
. Among the six compounds, only
12
and
17
undergo a well‐behaved, nearly reversible and a quasi‐reversible reduction process, respectively, indicating that two NCS or N(CN)
2
ligands contribute to the stabilization of their reduced states. |
|---|---|
| ISSN: | 0947-6539 1521-3765 |
| DOI: | 10.1002/chem.200801774 |