Reaction o
f [NBu
n4][
closo-1-CB
7H
8] with [Fe
2(CO)
9] in re
fluxing THF (tetrahydro
furan) gives the neutral
ferradicarborane [2,2,2-(CO)
3-1-OH-
closo-2,1,10-FeC
2B
7H
8] (
3), which, upon treatment with PEt
3 in the presence o
f Me
3NO, yields [2,2-(CO)
2-2-PEt
3-1-OH-
closo-2,1,10-FeC
2B
7H
8] (
4). In
3 and 4 the 10-vertex {FeC
2B
7} cluster has two carbon vertices in antipodal,
four-connected positions
and the iron atom in a
five-coordinate site adjacent to a carbon vertex that bears an OH substituent. Treatment o
f 4 in THF with NaH
and then R−X (X = Br, I) a
ffords [2,2-(CO)
2-2-PEt
3-1-OR-
closo-2,1,10-FeC
2B
7H
8] (R = Me (
5), CH
2CH
![](http://pubs.acs.org/images/entities/dbd_2.gi<font color=)
f">CH
2 (
6), CH
2C
![](http://pubs.acs.org/images/entities/tbd1.gi<font color=)
f">CH (
7), CH
2C
![](http://pubs.acs.org/images/entities/tbd1.gi<font color=)
f">CMe (
8)). The pendant allyl group in
6 becomes η
2-bonded to the iron center upon treatment with Me
3NO in CH
2Cl
2, giving [2-CO-2-PEt
3-1,2-σ:η
2-OCH
2CH
![](http://pubs.acs.org/images/entities/dbd_2.gi<font color=)
f">CH
2-
closo-2,1,10-FeC
2B
7H
8] (
9), which then with CNXyl (Xyl = C
6H
3Me
2-2,6) in the presence o
f PEt
3 gives [2,2-(CNXyl)
2-2-PEt
3-1-OCH
2CH
![](http://pubs.acs.org/images/entities/dbd_2.gi<font color=)
f">CH
2-
closo-2,1,10-FeC
2B
7H
8] (
10). Reaction between compound
7 and [Co
2(CO)
8] in petroleum ether yields [2,2-(CO)
2-2-PEt
3-1-{OCH
2-(μ-η
2:η
2-C
![](http://pubs.acs.org/images/entities/tbd1.gi<font color=)
f">CH)Co
2(CO)
6}-
closo-2,1,10-FeC
2B
7H
8] (
12), in which a {C
2Co
2} tetrahedron is linked to the 10-vertex {FeC
2B
7} cluster by an −OCH
2− bridge. Heating compound
7 with [Co(CO)
2(η-C
5H
5)] in re
fluxing toluene gives the complex [2,2-(CO)
2-2-PEt
3-1,4-μ-{OC(H)
![](http://pubs.acs.org/images/entities/dbd_2.gi<font color=)
f">C(Me)-
B}-
closo-2,1,10-FeC
2B
7H
7] (
13a), which contains a 5-membered ring that involves one carbon vertex
and an adjacent boron atom. Compound
13a yields [2-CO-2,2-(PEt
3)
2-1,4-μ-{OC(H)
![](http://pubs.acs.org/images/entities/dbd_2.gi<font color=)
f">C(Me)-
B}-
closo-2,1,10-FeC
2B
7H
7] (
13b) upon addition o
f further PEt
3 in the presence o
f Me
3NO. Treatment o
f compounds
7 and 8 with PEt
3 in CH
2Cl
2 and in the presence o
f Me
3NO a
ffords the zwitterionic ylide species [2-CO-2-PEt
3-1,2-μ-{OCH
2C{
![](http://pubs.acs.org/images/entities/dbd_2.gi<font color=)
f">C(R′)PEt
3}}-
closo-2,1,10-FeC
2B
7H
8] (R′ = H (
15), Me (
17), respectively). In the latter pair, an −OCH
2C{
![](http://pubs.acs.org/images/entities/dbd_2.gi<font color=)
f">C(R′)PEt
3} group bonded to a cage carbon atom is also directly σ-bonded (at the β-position) to the adjacent iron vertex,
forming a 5-membered ring. The novel structural
features o
f compounds
4,
10,
12,
13,
15,
and 17 have been con
firmed by single-crystal X-ray di
ffraction studies.