【作者】 张敏；

【导师】 刘子忠；

【作者基本信息】 内蒙古师范大学 ， 物理化学， 2011， 硕士

【摘要】 氟化物是一类重要的化合物,其数目庞大、种类繁多,一直是化学界令人感兴趣的研究课题之一。氟代苯等作为有机氟的基本原料越来越普遍地应用在染料、感光材料、航天等尖端技术,聚合材料以及农药和医药等方面,关于含氟化合物结构和性质的研究引起了人们极大的兴趣。但是关于氟代苯C6FmH6-m(m=1-6)的研究较少,C6Fm-H6-m(m=1-6)与过渡金属形成的半三明治、三明治的系统性理论研究未见报道。本文运用Gaussian03量子化学程序,采用密度泛函理论(DFT)的B3LYP/6-31 G(d,p)计算方法对氟代苯C6FmH6-m(m=1-6)及其铬半三明治和三明治配合物进行了几何结构优化、频率分析及键能分析。采用B3LYP-GIAO/6-31 ++ G(d,p)计算方法计算了所研究体系优化几何结构的NICS,并用NBO计算程序对不同空间点处各种化学键、各原子核对总NICS贡献进行了分解。对氟取代苯C6FmH6-m(m=1-6)进行结构和芳香性研究结果表明：所研究的氟代苯的基态均呈平面几何结构,其芳香性都较苯的大,且随取代F数目的增加而增大。用NBO对分子总NICS及各键对NICS的贡献进行了分解,结果显示,氟的pz孤对电子参与六元环π键的形成,是使氟代苯分子芳香性变大的主要原因。对半三明治配合物(η6-1,4-C6F2H4)Cr和(η6-C6F6)Cr研究结果表明：所研究的两个半三明治的基态稳定结构分别为C2v和C6v构型,均具有较强的中心芳香性、内芳香性及外芳香性,且其芳香性大于对应单环。半三明治芳香性的顺序是(η6-C6F6)Cr < (η6-1,4-C6F2H4)Cr<(η6-C6H6)Cr。芳香性主要来源于金属与配体间σ、π和δ三种相互作用。对三明治配合物(η6-C6F6)2Cr和(η6-1,4-C6F2H4)2Cr研究表明：两种三明治配合物的基态结构分别呈D6d和D2对称性,均为分步解离。同样有较强的中心芳香性、内芳香性及外芳香性。其芳香性大于对应的配体,小于对应的半三明治配合物。其芳香性的顺序为(η6-C6F6)2Cr<(η6-1,4-C6F2H4)2Cr<(η6-C6H6)2Cr,芳香性主要来源于金属与配体间σ、π和δ三种相互作用。对异层三明治配合物(η6-C6H6)Cr(η6-C6F6).(η6-C6H6)Cr(η6-1,4-C6F2H4)、和(η6-C6F6)Cr(η6-1,4-C6F2H4)的研究表明：三个三明治配合物的基态结构分别呈C6v(交错)、C1和C2v(交错)对称性,所研究的三明治均为分步解离,其中(η6-C6H6)Cr(η6-C6F6)C6v交错构型最稳定。配合物都具有较强的中心芳香性、内芳香性和较弱的外芳香性,且芳香性均比三种对应自由配体大,比对应半三明治配合物小。金属与配体间存在的σ、π和δ三种相互作用是芳香性变大的主要原因。更多还原

【Abstract】 Fluoro-compounds is a kind of important compounds. It is always one of the attractive research topics, because of its huge numbers and various kinds.With the developments of dyes, photographic materials, spaceflight technologies, polymer materials, pesticides and medicine, etc, fluorobenz-ene and other fluorinated benzenes as the basic raw materials of organic fluorine are widely used, so people are interested in the nature of the fluorine-containing compounds. However, the systemic study of C6FmH6-m and its sandwich complexes (C6FmH6-m)2Cr(m=1-6) are few.These are calculated for the geometries, frequencies, bonding energies and NICS of C6FmH6-m and (C6FmH6-m)2Cr (m=1-6). All calculations are performed with Gaussian 03 program using DFT/B3LYP method. The geometries and frequencies are calculated with 6-31 G(d,p) basis set.The NICS are calculated with 6-31 ++ G(d,p) basis set. In order to study the total NICS distribution in ligand plane and the various bond NICS contributions, the total NICS has been dissected into NICS contributions of various bonds, cores, and lone pair electronics by NBO.The results, calculated the eguilibrium geometries, frequencies, bonding energies and aromaticities of C6FmH6-m(m=1-6), indicate that all fluorinated benzenes are more aromatic than benzene, and the aromaticity increases with the number of F in C6FmH6-m(m=1-6). The various dissected bond NICSs reveal that the pz lone pair electrons of F atoms play a dominant role in the aromaticity of C6FmH6-m(m=1-6), and participate in formation ofπcurrent of the hexagon.The results, studied the eguilibrium geometries, frequencies, bonding energies and aromaticities of (η6-C6F6)Cr, (η6-1,4-C6F2H4)Cr, indicate that the ground states of them are C6v, C2v symmetries, respectively. The complexes have central, inner, outer aromaticities which are more aromatic than C6F6, 1,4-C6F2H4, respectively. There are three types of interactions asσ,πandδbetween the ligands and metal. The aromatic order of the half-sandwiches is (η6-C6F6)Cr< (η6-1,4-C6F2H4)Cr< (η6-C6H6)Cr.The results, analyzed the eguilibrium geometries, frequencies, bonding energies and aromaticities of sandwiches (η6-C6F6)2Cr, (η6-1,4-C6F2H4)2Cr, indicate that the ground states of them are D6d, D2 symmetries, respectively. The complexes have central, inner, outer aromaticities which are more aromatic than C6F6,1,4-C6F2H4 and less than (η6-C6F6)Cr, (η6-1,4-C6F2H4)Cr respectively. There are three types of interactions asσ,πandδbetween the ligands and metal. The aromatic order of the sandwiches is (η6-C6F6)2Cr (η6-1,4-C6F2H4)2Cr< (η6-C6H6)2Cr.The eguilibrium geometries, frequencies, bonding energies and aromaticities of sandwiches (η6-C6H6)Cr(η6-C6F6), (η6-C6H6)Cr(η6-1,4C6F2H4) and (η6-C6F6)Cr(η6-1,4-C6F2H4) are analyzed. The results indicate that the ground states of them are C6v(staggered), C1, C2v(staggered) symmetries, respectively. (η6-C6H6)Cr(η6-C6F6) C6v (staggered) is the most stable. The complexes have central, inner, outer aromaticities which are more aromatic than the responding ligand, and less aromatic than the responding half sandwich compound. The aromaticity increases due to three types of interactions asσ,πandδbetween the ligands and metal.更多还原