f-Element Half-Sandwich Complexes: A Tetrasilylcyclobutadienyl-Uranium(IV)-Tris(tetrahydroborate) Anion Pianostool Complex
f-Element Half-Sandwich Complexes: A Tetrasilylcyclobutadienyl-Uranium(IV)-Tris(tetrahydroborate) Anion Pianostool Complex
复制标题
f 元素半夹心配合物：四甲硅烷基环丁二烯基-铀(IV)-三(四氢硼酸盐)阴离子钢琴凳配合物
DOI：
10.1002/ange.201913640
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发表时间：
2019
影响因子：
--
通讯作者：
Boronski J
中科院分区：
文献类型：
--
作者：
Boronski J
Despite there being numerous examples of f‐element compounds supported by cyclopentadienyl, arene, cycloheptatrienyl, and cyclooctatetraenyl ligands (C5–8), cyclobutadienyl (C4) complexes remain exceedingly rare. Here, we report that reaction of [Li2{C4(SiMe3)4}(THF)2] (1) with [U(BH4)3(THF)2] (2) gives the pianostool complex [U{C4(SiMe3)4}(BH4)3][Li(THF)4] (3), where use of a borohydride and preformed C4‐unit circumvents difficulties in product isolation and closing a C4‐ring at uranium. Complex3is an unprecedented example of an f‐element half‐sandwich cyclobutadienyl complex, and it is only the second example of an actinide‐cyclobutadienyl complex, the other being an inverse‐sandwich. The U−C distances are short (av. 2.513 Å), reflecting the formal 2− charge of the C4‐unit, and the SiMe3groups are displaced from the C4‐plane, which we propose maximises U−C4orbital overlap. DFT calculations identify two quasi‐degenerate U−C4π‐bonds utilising the ψ2and ψ3molecular orbitals of the C4‐unit, but the potential δ‐bond using the ψ4orbital is vacant.
