Synthesis and reactivity of
[O![[upper bond 1 start]](https://www.rsc.org/images/entities/char_e010.gif)
sH{C6H4(CH![[double bond, length as m-dash]](https://www.rsc.org/images/entities/char_e001.gif)
CH![[upper bond 1 end]](https://www.rsc.org/images/entities/char_e011.gif)
H)
}(CO)(PPri3)2] and the formato
compounds
[Os{(E )-CHCHPh}(η2-O
2CH)(CO)(PPri3)2] and
[OsH(η2-O2CH)(CO)(PPri3)
2]*
Abstract
The complex
[OsH{C
6
H
4
(CHCH<H)
}(CO)(PPr
i
3
)
2
] has been prepared by
reaction of the five-co-ordinate
[Os{(E )-CHCHPh}Cl(CO)(PPr
i
3
)
2
] with LiBu
n
in hexane. It reacts with
P(OMe)
3
and CO to give [OsH{(E
)-
CHCHPh}(CO){P(OMe)
3
}(PPr
i
3
)
2
] and
[OsH{(E )-CHCHPh}(CO)
2
(PPr
i
3
)
2
], while under a CO
2
atmosphere the formato derivative
[Os{(E )-CHCHPh}(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
] is obtained.
Carbonylation of the latter leads to the monodentate formato complex
[Os{(E )-CHCHPh}{η
1
-
OC(O)H}(CO)
2
(PPr
i
3
)
2
] and
under a hydrogen atmosphere it affords styrene and
[OsH(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
], which can be also prepared by reaction of
[OsH
2
(η
2
-CH
2
CHEt)(CO)(PPr
i
3
)
2
] with CO
2
. The complex
[OsH(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
] reacts with CO, P(OMe)
3
and
MeO
2
CC![[triple bond, length as m-dash]](https://www.rsc.org/images/entities/char_e002.gif)
CCO
2
Me to give
[OsH{η
1
-OC(O)H}(CO)L(PPr
i
3
)
2
] [L = CO, P(OMe)
3
or
MeO
2
CC CCO
2
Me]; the carbon atom of its
formate ligand is attacked by NEt
2
H leading to the carbamato
compound
[OsH(η
2
-O
2
CNEt
2
)(CO)(PPr
i
3
)
2
] and molecular hydrogen. Similarly treatment of
[Os{(E )-CHCHPh}(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
] with
NEt
2
H afforded
[Os{(E )-CHCHPh}(η
2
-O
2
CNEt
2
)(CO)(PPr
i
3
)
2
]. The former complex also reacts with
HBF
4
·OEt
2
, giving two different derivatives
depending upon the conditions: in diethyl ether as solvent and in the
presence of acetonitrile the vinyl complex
[Os{(E )-CHCHPh}(CO)(MeCN)
2
(PPr
i
3
)
2
]BF
4
is formed,
while the carbene derivative
[Os(η
2
-O
2
CH)(CHCH
2
Ph)(CO)(PPr
i
3
)
2
]BF
4
is obtained in
chloroform. The products formed by reaction of
[OsH(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
] with HBF
4
·OEt
2
also depend upon
the reaction conditions: in diethyl ether and in the presence of MeCN the
hydrido compound
[OsH(CO)(MeCN)
2
(PPr
i
3
)
2
]BF
4
is obtained; however a mixture of products, mainly dihydrogen
derivatives, is formed in CDCl
3
. On the basis of theoretical
calculations and T
1
measurements, the nature and
structure of these dihydrogen compounds are discussed.
sH{C
6
H
4
(CHCH<H)
}(CO)(PPr
i
3
)
2
] has been prepared by
reaction of the five-co-ordinate
[Os{(E )-CHCHPh}Cl(CO)(PPr
i
3
)
2
] with LiBu
n
in hexane. It reacts with
P(OMe)
3
and CO to give [OsH{(E)-
CHCHPh}(CO){P(OMe)
3
}(PPr
i
3
)
2
] and
[OsH{(E )-CHCHPh}(CO)
2
(PPr
i
3
)
2
], while under a CO
2
atmosphere the formato derivative
[Os{(E )-CHCHPh}(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
] is obtained.
Carbonylation of the latter leads to the monodentate formato complex
[Os{(E )-CHCHPh}{η
1
-
OC(O)H}(CO)
2
(PPr
i
3
)
2
] and
under a hydrogen atmosphere it affords styrene and
[OsH(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
], which can be also prepared by reaction of
[OsH
2
(η
2
-CH
2
CHEt)(CO)(PPr
i
3
)
2
] with CO
2
. The complex
[OsH(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
] reacts with CO, P(OMe)
3
and
MeO
2
CCCCO
2
Me to give
[OsH{η
1
-OC(O)H}(CO)L(PPr
i
3
)
2
] [L = CO, P(OMe)
3
or
MeO
2
CC CCO
2
Me]; the carbon atom of its
formate ligand is attacked by NEt
2
H leading to the carbamato
compound
[OsH(η
2
-O
2
CNEt
2
)(CO)(PPr
i
3
)
2
] and molecular hydrogen. Similarly treatment of
[Os{(E )-CHCHPh}(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
] with
NEt
2
H afforded
[Os{(E )-CHCHPh}(η
2
-O
2
CNEt
2
)(CO)(PPr
i
3
)
2
]. The former complex also reacts with
HBF
4
·OEt
2
, giving two different derivatives
depending upon the conditions: in diethyl ether as solvent and in the
presence of acetonitrile the vinyl complex
[Os{(E )-CHCHPh}(CO)(MeCN)
2
(PPr
i
3
)
2
]BF
4
is formed,
while the carbene derivative
[Os(η
2
-O
2
CH)(CHCH
2
Ph)(CO)(PPr
i
3
)
2
]BF
4
is obtained in
chloroform. The products formed by reaction of
[OsH(η
2
-O
2
CH)(CO)(PPr
i
3
)
2
] with HBF
4
·OEt
2
also depend upon
the reaction conditions: in diethyl ether and in the presence of MeCN the
hydrido compound
[OsH(CO)(MeCN)
2
(PPr
i
3
)
2
]BF
4
is obtained; however a mixture of products, mainly dihydrogen
derivatives, is formed in CDCl
3
. On the basis of theoretical
calculations and T
1
measurements, the nature and
structure of these dihydrogen compounds are discussed.
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![[upper bond 1 start]](https://www.rsc.org/images/entities/h2_char_e010.gif)
sH{C6H4(CH![[double bond, length as m-dash]](https://www.rsc.org/images/entities/h2_char_e001.gif)
CH![[upper bond 1 end]](https://www.rsc.org/images/entities/h2_char_e011.gif)
H)
}(CO)(PPri3)2] and the formato
compounds
[Os{(E )-CH