平面十二配位MB_(8)C_(4)(M=Ca,Sr,Ba)分子轮团簇的理论研究  

Theoretical Study of MB_(8)C_(4)(M=Ca,Sr,Ba)Molecular Wheels Clusters with Dodeca-coordination Number in Plane

作　　者：冯林雁 胡晓波 闫苗[1] 苗常青[1] 陈瑞 郭谨昌[2] 王迎进[1] FENG Linyan;HU Xiaobo;YAN Miao;MIAO Changqing;CHEN Rui;GUO Jinchang;WANG Yingjin(Department of Chemistry,Xinzhou Teachers University,Xinzhou 034000,China;Nanocluster Laboratory,Institute of Molecular Science,Shanxi University,Taiyuan 030006,China)

机构地区：[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

出　　处：《高等学校化学学报》2023年第10期154-163,共10页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:22173053);山西省自然科学基金(批准号:202203021222305);山西省高等学校科技创新项目(批准号:2022L463);忻州师范学院科研基金(批准号:2021KY04)资助。

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, MB_(8)C_(4)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SrB_(8)C_(4)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BaB_(8)C_(4)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+)[B_(8)C_(4)]~(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.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 MB_(8)C_(4)(M=Ca,Sr,Ba)clusters.The results show that the global minimum structure of CaB_(8)C_(4) cluster adopts perfect planar molecular wheel structure.The centered calcium atom enclosed by a highly symmetric B_(8)C_(4) ring possesses the coordi-nate number(CN)of 12.The molecular wheel SrB_(8)C_(4) cluster has a C_(4)v 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 SrB_(8)C_(4) 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 MB_(8)C_(4)(M=Ca,Sr,Ba)molecular wheel can be formally described as[M]2+[B_(8)C_(4)]2-complexes.Chemical bonding analysis indicates that the dodeca-coordinated molecular wheel structure possesses 10σand 8πconflicting 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 B_(8)C_(4) 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

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 

分 类 号：O641[理学—物理化学]