高等学校化学学报 ›› 2023, Vol. 44 ›› Issue (10): 20230281.doi: 10.7503/cjcu20230281

• 物理化学 • 上一篇    

平面十二配位MB8C4(M=Ca, Sr, Ba)分子轮团簇的理论研究

冯林雁1, 胡晓波1, 闫苗1, 苗常青1, 陈瑞1, 郭谨昌2(), 王迎进1()   

  1. 1.忻州师范学院化学系, 忻州 034000
    2.山西大学分子科学研究所, 纳米团簇实验室, 太原 030006
  • 收稿日期:2023-06-14 出版日期:2023-10-10 发布日期:2023-08-14
  • 通讯作者: 王迎进 E-mail:guojc@sxu.edu.cn;yingjinwang@sxu.edu.cn
  • 作者简介:郭谨昌, 男, 博士, 教授, 主要从事计算化学方面的研究. E-mail: guojc@sxu.edu.cn
  • 基金资助:
    国家自然科学基金(22173053);山西省自然科学基金(202203021222305);山西省高等学校科技创新项目(2022L463);忻州师范学院科研基金(2021KY04)

Theoretical Study of MB8C4(M=Ca, Sr, Ba) Molecular Wheels Clusters with Dodeca-coordination Number in Plane

FENG Linyan1, HU Xiaobo1, YAN Miao1, MIAO Changqing1, CHEN Rui1, GUO Jinchang2(), WANG Yingjin1()   

  1. 1.Department of Chemistry,Xinzhou Teachers University,Xinzhou 034000,China
    2.Nanocluster Laboratory,Institute of Molecular Science,Shanxi University,Taiyuan 030006,China
  • Received:2023-06-14 Online:2023-10-10 Published:2023-08-14
  • Contact: WANG Yingjin E-mail:guojc@sxu.edu.cn;yingjinwang@sxu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(22173053);the Natural Science Foundation of Shanxi Province, China(202203021222305);the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province, China(2022L463);the Project of Xinzhou Teachers University, China(2021KY04)

摘要:

基于第一性原理计算, 在B3LYP/def2-TZVP水平下对碱土金属(Ca, Sr, Ba)掺杂的硼碳环团簇的稳定性、 化学成键及芳香性进行研究. 结果表明, CaB8C4团簇的全局极小结构是以Ca为中心的完美平面分子轮. 对于SrB8C4团簇, 十二配位分子轮和拉长状八配位结构能量相近, 可能共存于其异构体中. 随着掺杂金属原子半径的增加, 拉长状八配位结构逐渐趋于稳定, 为BaB8C4团簇的基态结构. 电荷分析结果表明, 轮状结构是一个高电荷转移化合物, 可被视为[M]2+[B8C4]2-离子复合物. 成键分析揭示分子轮结构具有10σ/8π冲突芳香性, 且中心金属与外围硼碳环之间存在微弱的共价作用. 磁感应环电流密度分析进一步证实轮状结构的成键特征. 该体系可视为双重芳香轮状结构的一个反例. 拟合出了体系的红外光谱, 并对主要特征峰进行了归属分析.

关键词: 硼基纳米团簇, 分子轮, 密度泛函理论, 化学成键, 芳香性

Abstract:

Searching for the maximum coordination number in planar species has attracted considerable attention from scientists. Although transition metal-centered boron molecular wheel haven been reported previously, there are relatively few studies on molecular wheel structures doped with main group metals. In this work, the geometric structures, chemical bonding, and aromaticity are investigated systemically at the B3LYP/def2-TZVP level for MB8C4(M=Ca, Sr, Ba) clusters. The results show that the global minimum structure of CaB8C4 cluster adopts perfect planar molecular wheel structure. The centered calcium atom enclosed by a highly symmetric B8C4 ring possesses the coordinate number(CN) of 12. The molecular wheel SrB8C4 cluster has a C4v symmetry with the out-of-plane distortion of the Sr atom, which are close in energy with elongated boron-carbon ring at CCSD(T)/def2-TZVP level. The latter has the actual coordination number of 8. Using a Ba, a larger atomic radius, to replace Sr in SrB8C4 cluster, the molecular wheel structure becomes less stable than elongated boron-carbon ring at CCSD(T)/def2-TZVP level. The natural bond orbital(NBO) analyses show that these systems undergo a large amount of charge transfer from alkaline earth metals to boron-carbon motifs. The MB8C4(M=Ca, Sr, Ba) molecular wheel can be formally described as [M]2+[B8C42- complexes. Chemical bonding analysis indicates that the dodeca-coordinated molecular wheel structure possesses 10σ and 8π conflicting aromaticity, which represents a counterexample in planar hyper-coordinated species. Adaptive natural density partitioning(AdNDP) analysis reveals that the interaction between the central alkaline earth metal and peripheral B8C4 monocyclic ring is governed by electrostatics and weakly covalent interaction. The latter mainly originate from contributions involving the M nd atomic orbitals, implying that alkaline earth metals mimic the behavior of transition metals. In addition, both the ring currents induced by an external magnetic field and the electron localization functions analysis results confirm the bonding characteristics of molecular wheel structures. We also predicted the infrared spectra of molecular wheel and elongated boron-carbon ring isomers, which provide theoretical guidance for experimental characterization of these clusters in future.

Key words: Boron-based nanoclusters, Molecular wheel, Density functional theory, Chemical bonding, Aromaticity

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