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利用 B3LYP法在 6-31 1 +G* 水平上研究了 Na-噻吩体系可能存在的 3种 Na-噻吩复合物 A,B和 C分子结构 .结果表明 :Na-噻吩体系存在 2个能量极小结构 A和 C;结构 B未得到证实 .结构 A中 ,Na的 3s1电子直接和噻吩杂环的所有重原子进行弱相互作用形成一个具有 Cs对称性的金属有机复合物 ;结构 C中 ,Na原子的 3s1电子主要通过和与 S原子不直接相连的 C2和 C3进行弱相互作用 ,因而在原有的大 π键基础上形成一个新的大 π键 ,其结构为 C2 v对称性 .结构 A较结构 C稳定 78.0 k J/ mol.结构 A中的 Na—S之间的距离为 0 .4 0 7nm,键角∠ CSC为 91°,金属 Na和噻吩之间的弱相互作用使整个噻吩分子平面稍微变形 ,S原子向 Na所在的一侧稍微偏离 C环平面 .结构 C中 Na-S之间的距离为 0 .82 5 nm,∠ CSC为 91°,金属 Na原子和杂环中所有的原子在同一个平面内 .在 B3LYP、 MP2、 MP3和 MP4水平上 ,分别用 6-31 1 +G* 和 6-31 1 ++G* * 基组精确计算了最稳定结构 A的结合能 ΔE为 8.3～ 1 0 .9k J/ mo
The B3LYP method was used to study the possible molecular structures of three Na-thiophene complexes A, B and C at the level of 6-31 1 + G * in Na-thiophene system. The results show that there are two small energy Structure A and C; structure B is unconfirmed.In structure A, 3s1 electron of Na directly interacts weakly with all heavy atoms of thiophene heterocycle to form a metal-organic complex with Cs symmetry; in structure C, Na atom Of the 3s1 electrons are mainly weakly interacting with C2 and C3, which are not directly connected to the S atom, so that a new large π bond is formed on the basis of the original large π bond and the structure is C2 v symmetry. C is stable at 78.0 kJ / mol. The distance between Na-S in structure A is 0.4007nm and the bond angle CSC is 91 °. The weak interaction between metal Na and thiophene makes the entire thiophene molecular plane slightly Deformation, S atoms to the side of Na a little deviation from the C ring plane structure C Na-S distance between the 0.82 5 nm, CSC ∠ 91 °, the metal Na atoms and all the atoms in the heterocyclic ring in the In the same plane, B3LYP, MP2, MP3 and MP4 levels, respectively, with 6-31 1 + G * And 6-31 1 ++ G * * basis set accurately calculated the most stable structure A binding energy ΔE 8.3 ~ 109kJ / mo