超原子6电子和8电子配置的M@Au24(SR) 18集群之间的相互转换 (M = Pd, Pt)
Kyuju Kwak1, Qing Tang2, Minseok Kim1
1Department of Chemistry, Yonsei University , Seoul 120-749, Korea.
Journal of the American Chemical Society
|July 30, 2015
概括
用或添加的硫酸盐保护黄金集群表现出稳定的6电子配置,与纯金集群的8电子配置不同. 这种兴奋剂显著减少了最高占成的分子轨道 - 最低的未占用的分子轨道间隙,改变了电子结构.
科学领域:
- 纳米材料化学
- 超原子集群化学
- 计算化学
背景情况:
- 由硫酸盐保护的黄金集群,特别是[Au25 ((SR) 18 ((-),由于封闭的超原子电子外 (8电子配置) 实现了特殊的稳定性.
- 了解金属集群的电子结构和稳定性对于开发新的功能纳米材料至关重要.
研究的目的:
- 用 (Pd) 或 (Pt) 替代[Au25(SR) 18) 的核心黄金原子的效果.
- 描述由此产生的[MAu24(SR) ] (M = Pd, Pt) 集群的电子结构,稳定性和几何性质.
- 探索不同超原子电子配置之间的相互转换.
主要方法:
- 用酸盐保护的金和金集的合成和表征 ([PdAu24(SR) 18) ((0) 和[PtAu24(SR) 18) ((0)).
- 电压测量研究以确定最高占成的分子轨道-最低不占成的分子轨道 (HOMO-LUMO) 间隙.
- 密度函数理论 (DFT) 调查以确认电子结构和分析几何优化.
主要成果:
- 合成了稳定的[MAu24 ((SR) 18 ((0)) 集群 (M = Pd, Pt),表现出一个超原子的6电子配置.
- 电压测量和DFT计算显示,与[Au25(SR) 18) ((-1,35) eV相比,HOMO-LUMO差距显著减少.
- 在6电子集群中观察到MAu12核心的Jahn-Teller-like扭曲,导致1P轨道的分裂.
- 这些杂集群显示可逆电子充电形成8电子[MAu24(SR) 18) ((2-) 集群.
结论:
- 在Au25集群中用Pd或Pt取代核心黄金原子会导致具有显著变化的电子性质的稳定6电子超原子配置.
- 观察到的HOMO-LUMO间隙的减少归因于6电子杂集群中的Jahn-Teller-like扭曲.
- 在这些新型合黄金集群中,可以实现6电子和8电子配置之间的可逆互换.
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