Competition between drum and quasi-planar structures in RhB(18)(-): motifs for metallo-boronanotubes and metallo-borophenes.
Competition between drum and quasi-planar structures in RhB(18)(-): motifs for metallo-boronanotubes and metallo-borophenes.
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RhB18 中鼓形结构和准平面结构之间的竞争：金属硼纳米管和金属硼烯的图案
DOI：
10.1039/c6sc02623k
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发表时间：
2016-12-01
期刊：
影响因子：
8.4
通讯作者：
Wang LS
中科院分区：
文献类型：
--
作者：
Jian T;Li WL;Chen X;Chen TT;Lopez GV;Li J;Wang LS
在气态RhB18簇合物中发现了两个近乎简并的异构体，一个是鼓状的，另一个是准平面的，揭示了金属硼阳极管和金属硼烯结构之间的竞争。金属掺杂的硼团簇为设计具有有趣的结构和成键的纳米团簇提供了新的机会。最近观察到钴掺杂的硼团簇CoB18-是平面的，可以看作是金属硼烯的模体，而D 9d鼓状异构体作为金属硼管的模体的能量要高得多。因此，是否可能有更大的掺杂硼桶仍然是一个悬而未决的问题。在这里，我们报道了对于RhB18，鼓形结构和准平面结构在能量上变得更加接近，并在实验上共存，揭示了金属硼阳极管和金属硼烯结构之间的竞争。RhB18-的光电子能谱显示出复杂的光谱模式，表明存在两个异构体。量子化学研究表明，D-9D鼓型异构体和准平面异构体(C-S)争夺全局极小值。RhB18-中鼓状异构体稳定性的提高是由于Rh 4d轨道收缩较少，可以与B18鼓状基序发生良好的相互作用。化学键分析表明，RhB18-的准平面异构体是芳香族的，电子数为10π，而观察到的RhB18-鼓团簇在金属络合物中的配位数为18。目前的发现表明，硼鼓的大小可以通过适当的金属掺杂剂来调节，这表明，甚至更大的含有5d、6d过渡金属、镧系元素或鳗系金属原子的硼鼓也是可能的。
Two nearly degenerate isomers, one a drum and the other quasi-planar, are discovered for the gaseous RhB18 – cluster, revealing a competition between the metallo-boronanotube and metallo-borophene structures. Metal-doped boron clusters provide new opportunities to design nanoclusters with interesting structures and bonding. A cobalt-doped boron cluster, CoB18 –, has been observed recently to be planar and can be viewed as a motif for metallo-borophenes, whereas the D 9d drum isomer as a motif for metallo-boronanotubes is found to be much higher in energy. Hence, whether larger doped boron drums are possible is still an open question. Here we report that for RhB18 – the drum and quasi-planar structures become much closer in energy and co-exist experimentally, revealing a competition between the metallo-boronanotube and metallo-borophene structures. Photoelectron spectroscopy of RhB18 – shows a complicated spectral pattern, suggesting the presence of two isomers. Quantum chemistry studies indicate that the D 9d drum isomer and a quasi-planar isomer (C s) compete for the global minimum. The enhanced stability of the drum isomer in RhB18 – is due to the less contracted Rh 4d orbitals, which can have favorable interactions with the B18 drum motif. Chemical bonding analyses show that the quasi-planar isomer of RhB18 – is aromatic with 10 π electrons, whereas the observed RhB18 – drum cluster sets a new record for coordination number of eighteen among metal complexes. The current finding shows that the size of the boron drum can be tuned by appropriate metal dopants, suggesting that even larger boron drums with 5d, 6d transition metal, lanthanide or actinide metal atoms are possible.