科研之友
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摘要
Boron-based nanoclusters have unique structures, bonding, and dynamic properties, which originate from boron's electron-deficiency. We demonstrate here that pouring in extra electrons can alter such systems fundamentally. A coaxial triple-layered Be6B102- sandwich cluster is designed via global structural searches and quantum chemical calculations. It is well defined as the global minimum, which consists of a slightly elongated B-10 monocyclic ring and two Be-3 rings, the latter forming a Be-6 trigonal-prism albeit without interlayer Be-Be bonding. The B-10 ring shows structural and chemical integrity with respect to the Be-3 rings, and yet it differs markedly from the free B-10 cluster and closely resembles the C-10 cluster. The present data testify to the idea of electronic transmutation, in which a B- is equivalent to C and a B-10 cluster, upon charge-transfer, is converted to and stabilized as a monocyclic ring analogous to C-10. Chemical bonding analyses reveal that the B-10 ring in the Be6B102- cluster has 10 and 10 sigma delocalization and each Be-3 ring is held together by 2 sigma electrons, collectively rendering four-fold /sigma aromaticity. The bonding pattern is in line with the formula of [Be-3](4+)[B-10](10-)[Be-3](4+), suggesting a highly charged electron-transfer complex. Furthermore, the Be6B102- cluster is dynamically fluxional with dual modes of revolution (orbiting) and rotation (twisting), being structurally robust at least up to a temperature of 1500 K.
- 出版日期2018-9-21
- 单位山西大学; 忻州师范学院
