氫鍵與鹵鍵間之協同作用

The Cooperativity between Hydrogen Bond and Halogen Bond

吳毓崇(Yu-Chung Wu)

指導教授 ： 游靜惠

國立清華大學/理學院/化學系/碩士(2006年)

摘要

本文以分析X─HCN─HF、X─HCN─BrF、以及X─HCN─Br2三組具近似線性結構之三元體分子系統之氫鍵及鹵鍵鍵長與鍵能，來探討氫鍵與鹵鍵之間的協同性。在系統中X代表六種X-配基，分別為乙炔、水、氨、氯化氫、氰化氫以及氟化氫單體。本研究之理論計算是在Gaussian 98軟體中以MP2、mPW1PW91以及B3LYP三種理論方法並搭配6-311++G(d, p)基底函數來執行。在計算結果中，三元體的氫鍵與鹵鍵鍵長與鍵能顯示出不同的大小順序。針對氫鍵與鹵鍵鍵能依X-配基之不同所顯示的大小順序，我們應用Hammett方程式之概念來深入分析。在此分析當中，三組三元體系統中的氫鍵與鹵鍵之協同性與氰化氫右側鍵結之鍵能分別顯示三組直接的線性關係。此三組線性關係的截距代表沒有X-配基誘發的協同作用之HCN─HF、HCN─BrF、以及HCN─Br2三個二元體之鍵能，且與理論計算得出的二元體鍵能之誤差小於2.7 %。另一方面，此三組線性關係中的斜率顯示三元體系統中氫鍵和鹵鍵間之協同性對於X-配基之變化的靈敏度。基底重疊誤差對於斜率值造成的影響經比對發現其最大偏差為0.103，且並未改變在線性關係中所描述之氫鍵與鹵鍵間協同性之化學性質。透過斜率值，可以對本研究中三種獨立的三元體系統中氫鍵與鹵鍵間之協同性作有效的預測。

關鍵字

氫鍵 ； 鹵鍵 ； 協同性

並列摘要

The cooperativity between hydrogen bond and halogen bond is investigated by analyzing the bond energy and bond length of three sets of nearly linear trimer systems: X─HCN─HF, X─HCN─BrF, and X─HCN─Br2. The symbol X refers to X-ligand and includes C2H2, H2O, NH3, HCl, HCN, HF. Three computational levels, MP2, mPW1PW91, and B3LYP are used to carry out the theoretical computations with the 6-311++G(d, p) basis set in the Gaussian 98 package. Different sequences are observed in bond lengths and bond energies of the hydrogen bonds and halogen bonds in trimers. The concept of the Hammett equation is applied to examine the sequence of the hydrogen-bond and halogen-bond energies in trimers. Linear relationships between the cooperativity and the bond energies of the bonding between the nitrogen of HCN and hydrogen of HF in trimers are observed. The intercepts are found to be the corresponding dimer bond energies without cooperativity effects. The deviation of the intercepts from calculated dimer bond energies is less than 2.7 %. The BSSE effect on the linear correlations is examined, and it does not change the chemical properties of trimer systems with a variation less than 0.103 for the slopes of the linear correlation. The slopes of these linear correlations show the reaction sensitivity to the change of X-ligands in the interactions between hydrogen bond and halogen bond. By using the slopes, the cooperativity in the three trimer groups can be estimated with acceptable accuracy.

並列關鍵字

hydrogen bond ； halogen bond ； cooperativity