Heteroleptic actinocenes: a thorium()-cyclobutadienyl-cyclooctatetraenyl-di-potassium-cyclooctatetraenyl complex
Despite the vast array of η n -carbocyclic C 5-8 complexes reported for actinides, cyclobutadienyl (C 4 ) remain exceedingly rare, being restricted to six uranium examples. Here, overcoming the inherent challenges of installing highly reducing C 4 -ligands onto actinides when using polar starting ma...
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| Published in: | Chemical science (Cambridge) 2020-06, Vol.11 (26), p.6789-6794 |
|---|---|
| Main Authors: | , , |
| Format: | Article |
| Language: | eng |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Despite the vast array of η
n
-carbocyclic C
5-8
complexes reported for actinides, cyclobutadienyl (C
4
) remain exceedingly rare, being restricted to six uranium examples. Here, overcoming the inherent challenges of installing highly reducing C
4
-ligands onto actinides when using polar starting materials such as halides, we report that reaction of [Th(η
8
-C
8
H
8
)
2
] with [K
2
{C
4
(SiMe
3
)
4
}] gives [{Th(η
4
-C
4
[SiMe
3
]
4
)(μ-η
8
-C
8
H
8
)(μ-η
2
-C
8
H
8
)(K[C
6
H
5
Me]
2
)}
2
{K(C
6
H
5
Me)}{K}] (
1
), a new type of heteroleptic actinocene. Quantum chemical calculations suggest that the thorium ion engages in π- and δ-bonding to the η
4
-cyclobutadienyl and η
8
-cyclooctatetraenyl ligands, respectively. Furthermore, the coordination sphere of this bent thorocene analogue is supplemented by an η
2
-cyclooctatetraenyl interaction, which calculations suggest is composed of σ- and π-symmetry donations from in-plane in- and out-of-phase C&z.dbd;C 2p-orbital combinations to vacant thorium 6d orbitals. The characterisation data are consistent with this being a metal-alkene-type interaction that is integral to the bent structure and stability of this complex.
We report the first thorium-cyclobutadienyl complex, a new type of heteroleptic actinocene, that exhibits 'an alkene-like' thorium-η
2
-cyclooctatetraenyl interaction. |
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| ISSN: | 2041-6520 2041-6539 |