The Fischer method was employed to synthesize bimetallic monocarbene
complexes from lithiated
[Cr(SC
4
H
4
)(CO)
3
] and metal
hexacarbonyls. In addition to the formation of
[MC[η
5
-C
4
H
3
SCr(CO)
3
]OEt}(CO)
5
] (M = Cr 1 or W 2) the
complexes
[MC[η
5
-C
4
H
3
SCr(CO)
3
]O(CH
2
)
4
OEt}(CO)
5
]
(M = Cr 3 or W 4), were also obtained. The formation of 3
and 4 is ascribed to the activation of tetrahydrofuran (thf) by a
Ï,Ï-co-ordinated acyl metalate, which triggers the cleavage of
the thf ring and leads to its inclusion into the alkoxy substituent of
the resulting carbene moiety. In polar solvents the Cr(CO)
3
fragments are displaced to give known
pentacarbonyl[ethoxy(thienyl)carbene] complexes and the new mononuclear
carbene complexes
[MC(C
4
H
3
S)O(CH
2
)
4
OEt
}(CO)
5
] (M = Cr 5 or W 6). The analogous
benzo[b]thienyl carbene complex
[CrC[η
6
-C
8
H
5
SCr(CO)
3
]OEt}(CO)
5
] 7 was prepared similarly, but did not
afford the thf-inserted product and the corresponding conversion into
the mononuclear carbene complex
[CrC(C
8
H
5
S)OEt}(CO)
5
] 8, was
much slower.
采用费舍尔法从石化[Cr(SC 4 H 4 )(CO) 3 ]和
金属六羰基合成双
金属单羰基络合物。除了形成 [MC[δ- 5 -C 4 H 3 SCr(CO) 3 ]OEt}(CO) 5 ](M = Cr 1 或 W 2)络合物外,还得到了 [MC[δ- 5 -C 4 H 3 SCr(CO) 3 ]O(CH 2 ) 4 OEt}(CO) 5 ](M = Cr 3 或 W 4)络合物。3 和 4 的形成是由于
四氢呋喃(thf)被Ï,Ï-配位的酰基
金属酸盐活化,从而引发了thf 环的裂解,并导致其被纳入所产生的
碳烯分子的烷
氧基取代基中。在极性溶剂中,Cr(CO) 3 片段发生位移,生成已知的五羰基[乙
氧基(
噻吩基)
碳]配合物和新的单核
碳烯配合物 [MC(C 4 H 3 S)O(CH 2 ) 4 OEt }(CO) 5 ](M = Cr 5 或 W 6)。类似的
苯并[b]
噻吩碳络合物[CrC[δ- 6 -C 8 H 5 SCr(CO) 3 ]OEt}(CO) 5 ]也是这样制备的。类似地制备了 7,但没有得到插入thf的产物,相应地转化为单核
碳烯配合物[CrC(C 8 H 5 S)OEt}(CO) 5 ]8 的过程也要慢得多。