金属芳香性与环伸缩振动拉曼光谱频率相关性的理论研究

发布时间：2018-11-03 08:06

【摘要】：芳香性可用于解释芳香性体系的结构特点、成键特征及稳定性,还可以用来预测反应方向和指导新功能物质的合成。目前对于物质芳香性大小的度量只能通过理论计算途径来实现,至今没有找到可行的实验测定方法,探索可行的芳香性大小实验测定方法具有重要的研究价值。本研究运用群论知识对高对称环状分子进行简正振动对称性分析,研究发现芳香性分子均具有可测的环伸缩A1′/A1g振动方式的拉曼光谱。运用动力学Lagrange运动方程对芳香性分子的环伸缩振动研究表明其环伸缩振动位置坐标的变换与其力常数有关,且存在π和σ环流使其具有了芳香性进而增大原子间的相互作用力,即增大了原子间力常数,也增大了芳香性物质的稳定性。因此可以在实验水平上进行测定的高对称环状化合物的环伸缩振动(A1′/A1g)拉曼光谱振动频率(the Ring Stretching Vibration Roman Spectroscopy Frequency,RSVRSF)的大小,既是分子力常数大小的一种表现形式,又与芳香性有关,这样其RSVRSF必与其芳香性相关。具体计算采用Gaussian09程序中密度泛函B3LYP/6-311+G*和HF/6-311+G*方法,首先对平面金属[AlnHn]2-(n=3-6)、[BnHn]2-(n=3-6)体系进行几何优化和环伸缩振动(A1′/A1g)拉曼光谱振动频率RSVRSF计算,同时对其优化结构采用GIAO法计算其核独立化学位移(NICS),设计假想碎片反应计算其芳香性稳定化能(ASE),探索NICS、RSVRSF及ASE间的相关性。结果表明两种方法计算的RSVRSF与对应的NICS(min)/NICS(1.0)都呈现显著一次相关,[AlnHn]2-(n=3-6)、[BnHn]2-(n=3-6)体系的RSVRSF与对应的ASE分别呈现良好一次、二次相关,[AlnHn]2-(n=3-6)、[BnHn]2-(n=3-6)体系的NICS(min)/NICS(1.0)与对应的ASE分别呈现显著一次、二次相关。采用密度泛函B3LYP/6-311+G*方法对高对称环状平面结构[AlnXn]2-(X=F、Cl、Br,n=3-5)进行结构优化和RSVRSF、NICS(0.0)/NICS(1.0)/NICS(min)、ASE计算,并讨论它们之间的相关性。结果发现[Al3X3]2-(X=F、Cl、Br)的RSVRSF值与对应的NICS(min/0.0)/NICS(1.0)数值间的相关性最好,且为显著一次相关,[Al5X5]2-(X=F、Cl、Br)的相关性其次,[Al4X4]2-(X=F、Cl、Br)的相关性最差,为不显著相关。[Al3X3]2-(X=F、Cl、Br)体系的RSVRSF值与对应的ASE的相关性为显著一次相关,其NICS(min/0.0)/NICS(1.0)与ASE的相关性中三元环、五元环的相关性为显著一次相关,四元环的相关性不明显。采用B3LYP/6-311+G*方法对Al3-及全金属平面环状体系Xn(X=B、Al、Ga,n=3-6)的芳香性大小与环伸缩振动拉曼光谱RSVRSF的相关性也进行了理论研究,发现Xn(X=B、Al、Ga,n=3-6)体系的RSVRSF(A1/A1g)与NICS(min/0.0)/NICS(1.0)都表现出显著的二次相关性。从对目标体系的RSVRSF与芳香性的相关性的理论研究结果可知,RSVRSF可作为实验上测定目标体系物质的芳香性大小的实验测量值,通过实验测定RSVRSF值可测该类物质的芳香性的大小值。
[Abstract]:Aromaticity can be used to explain the structural characteristics, bonding characteristics and stability of aromatic systems. It can also be used to predict the reaction direction and guide the synthesis of new functional substances. At present, the measurement of the aromaticity of substances can only be realized by theoretical calculation, so far no feasible experimental method has been found, so it is of great value to explore the feasible experimental measurement method of aromaticity. In this study, the normal vibrational symmetry of highly symmetric ring molecules was analyzed by using group theory knowledge. It was found that aromatic molecules have the Raman spectra of the measurable cyclic stretching A1'/A1g vibration mode. The dynamic Lagrange equation of motion is used to study the cyclic stretching vibration of aromatic molecules. It is shown that the transformation of the position coordinates of the ring stretching vibration is related to its force constant, and the existence of 蟺 and 蟽 circulation makes it aromatic and increases the interaction force between atoms. Both the interatomic force constant and the stability of aromatic substances are increased. Therefore, the magnitude of the ring stretching vibration (A1'/A1g) Raman spectrum vibration frequency (the Ring Stretching Vibration Roman Spectroscopy Frequency,RSVRSF) of a highly symmetric ring compound, which can be measured at the experimental level, is a form of expression of the molecular force constant. And aromaticity, so its RSVRSF must be related to its aromaticity. The density functional B3LYP/6-311 G* and HF/6-311 G* methods in the Gaussian09 program are used to calculate the plane metal [AlnHn] 2- (nnb3-6). The geometric optimization and A1'/A1g Raman spectrum vibration frequency RSVRSF calculation of [BnHn] 2- (nnc3-6) system were carried out. Meanwhile, the GIAO method was used to calculate the nuclear independent chemical shift (NICS), for its optimized structure. A hypothetical fragment reaction was designed to calculate its aromatic stabilization energy (ASE), to explore the correlation between NICS,RSVRSF and ASE. The results show that there is a significant correlation between the RSVRSF calculated by the two methods and the corresponding NICS (min) / NICS (1.0). The RSVRSF and the corresponding ASE of [AlnHn] 2- (nnc3- 6) and [BnHn] 2- (NC3-6) systems show a good one time, respectively. The NICS (min) / NICS (1. 0) of [AlnHn] 2- (nnc3-6) and [BnHn] 2- (nnc3-6) system were significantly correlated with the corresponding ASE, respectively. The density functional B3LYP/6-311 G* method was used to optimize the structure of [AlnXn] 2- (XFCClClBrnC5) and to calculate RSVRSF,NICS (0.0) / NICS (1.0) / NICS (min), ASE. The correlation between them is discussed. The results showed that the correlation between the RSVRSF value of [Al3X3] 2- (XFFU Clnbr) and the corresponding values of NICS (min/0.0) / NICS (1.0) was the best, and the correlation between [Al5X5] 2- (XFFCClCnbBr) was the second, The correlation of [Al4X4] 2- (XNFFCClCbBr) was the worst, which was not significant. The correlation between RSVRSF value of [Al3X3] 2- (XFCClCbBr) system and corresponding ASE was significant. The correlation between NICS (min/0.0) / NICS (1. 0) and ASE is significant in ternary ring, quaternion ring and quaternion ring. The correlation between the aromaticity of Al3- and the Xn (Xubb) AlGaN3-6 system and the cyclic vibrational Raman spectroscopy (RSVRSF) is also studied by B3LYP/6-311 G * method. It is found that Xn (XBX BU AlGaAlGa3-6) is an important component of the structure of Xn, and the relationship between the aromaticity of Al3- and the vibrational Raman spectrum of RSVRSF is also studied. RSVRSF (A1/A1g) and NICS (min/0.0) / NICS (1.0) showed significant quadratic correlation. From the theoretical study on the correlation between RSVRSF and aromaticity of the target system, it can be seen that RSVRSF can be used as the experimental value to measure the aromaticity of the target system, and RSVRSF can be used to measure the aromaticity of the target system.
【学位授予单位】：内蒙古师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.37

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