Al-Kahtani A A, Al-Jallal N A, El-Azhary A A
Chemistry Department, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
Chemistry Department, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Nov 11;132:70-83. doi: 10.1016/j.saa.2014.04.170. Epub 2014 May 14.
Conformational analysis was performed for the 18-crown-6-alkali metal cation complexes, 18c6-AMCCs, using the CONFLEX method. The number of predicted conformations of the 18c6-Li+, Na+, K+, Rb+ and Cs+ complexes was 10, 24, 15, 9 and 4 conformations, respectively. Electronic and geometrical structures were calculated for the predicted conformations at the HF, B3LYP, CAM-B3LYP, M06 and MP2 levels. Binding energies and enthalpies of the ground state conformations were also calculated. Vibrational, IR and Raman, spectra of free 18c6 and 18c6-AMCCs were measured. Comparison between the calculated vibrational frequencies using multi-scale-factor scaling of the B3LYP force field and the experimental vibrational frequencies predicted that the 18c6-K+, Rb+ and Cs+ complexes exist in the D3d, C3v and C3v conformations, respectively. It was also predicted that the 18c6-Na+ complex exists in a D3d-like conformation. It was not possible to identify in what conformation the 18c6-Li+ complex exists.
使用CONFLEX方法对18-冠-6-碱金属阳离子配合物（18c6-AMCCs）进行了构象分析。18c6-Li⁺、Na⁺、K⁺、Rb⁺和Cs⁺配合物的预测构象数分别为10、24、15、9和4种构象。在HF、B3LYP、CAM-B3LYP、M06和MP2水平上计算了预测构象的电子和几何结构。还计算了基态构象的结合能和焓。测量了游离18c6和18c6-AMCCs的振动光谱、红外光谱和拉曼光谱。使用B3LYP力场的多尺度因子标度计算的振动频率与实验振动频率之间的比较预测，18c6-K⁺、Rb⁺和Cs⁺配合物分别以D3d、C3v和C3v构象存在。还预测18c6-Na⁺配合物以类似D3d的构象存在。无法确定18c6-Li⁺配合物以何种构象存在。
