X-·H_2O(X=F,Cl,Br,I)复合物氢键红移光谱的理论研究

Theoretical Study on the Red-Shifting O-H…X-(X=F,C1,Br,I) Hydrogen Bonds of X-.H_2O(X=F,Cl,Br,I)Complexes

在B3LYP/6-311++G**[I-离子使用赝势基组(4s4pld)/(2s2pld)]水平下得到X-.H2O(X=F,Cl,Br,I)复合物优化构型。经MP2校正电子相关能及基组叠加误差(BSSE)在相同基组下单点校正,求得精确的单体间相互作用能的大小。由自然键轨道(NBO)分析揭示了相互作用的本质,阐述了相互作用的强度以及它对复合物构型和振动参数的影响。经分析得到电荷由X-离子的孤对电子迁移(CT)到σ*OH(…X)反键上,σ*OH(…X)的自然布居数增加,削弱了σOH(…X)键使σOH(…X)键增长,力常数变小,导致红移(与单体H2O相比),与实验值非常吻合,且它们之间具有很好的相关性,同时,红移强度加强。

The optimized geometries of X^-·H2O（X=F,Cl,Br,I） were obtained at B3LYP/6-311＋＋G^＊＊ [Valence electrons of I were treated with a basis set of （4s4pld/2s2pId）] level. And the accurate intermonomers interaction energy is calculated using the MP2 electron correlation correction and the basis set superposition error correction by the Boys-Bernardi ＂counterpoise＂ protocol. Natural Bond Orbital （NBO） Theory was applied to quantify the relative strength of these interactions and to account for their effect on stability, structural and vibrational parameters of X^-·H2O（X=F,Cl,Br,I）. It is shown that the charge transferred from the lone pair of X to the σ^＊OH（…X） antibonding orbital is importance. The results indicated the population of σ^＊OH（…X） orbitals increases, the σ^＊OH（…X） bond is lengthened, leading to the red-shifting, which is identical with the experiment value, and they are well correlated. At the same time, the intensity of red-shifting is strengthend.