QUANTUM CHEMISTRY STUDIES ON THE Fe-M INTERACTIONS AND 31P NMR IN[Fe(CO)3(MePhPpy)2(MCl2)](M=Zn,Cd,Hg)
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摘要: 应用密度泛函DFT理论PBE0方法对单核配合物[Fe(CO)3(MePhPpy)2]1、双核配合物[Fe(CO)3(MePhPpy)2(MCl2)]（2:M=Zn，3：M=Cd，4：M=Hg）和[Fe(CO)3(MePhPpy)2(HgCl2)2]5的结构进行了理论计算，研究了双核配合物中金属-金属间相互作用及其对31P化学位移的影响.结果表明：（1）配合物2～4的稳定性为243.（2）Fe-M相互作用的强弱顺序为234.（3）NBO分析得到Fe-M相互作用主要表现为Fe-PnM和Fe-CnM的电荷转移作用，而N-M的相互作用以nNnM离域作用为主.（4）用DFT-PBE0-GIAO方法计算1，3，5的31P化学位移值与实验值较接近，并预测了2和4的31P化学位移分别为61.66ppm和56.49ppm.（5）形成双核配合物后，Fe-C*Fe-P离域增大，而Fe-P*Fe-C减小，使得P原子核所受的屏蔽作用比1的大，故双核配合物的31P化学位移比单核配合物的小.Abstract: To study the metal-metal interactions and their effects on 31P NMR,the structures of mononuclear complex [Fe(CO)3(MePhPpy)2] 1,binuclear complexes [Fe(CO)3(MePhPpy)2(MCl2)]（2:M=Zn，3：M=Cd，4：M=Hg）and [Fe(CO)3(MePhPpy)2(HgCl2)2] 5 are calculated by density functional theory (DFT) PBE0 method.The following conclusions can be drawn as follows. (1)the stability of complexes is 243. (2)The Fe-M interactions is 234. (3)The Fe-M interactions mainly act as Fe-PnM and Fe-CnM charge-transfer interactions, and the N-M interactions mainly act as nNnM.（4）The calculated 31P chemical shifts in 1,3,5 are consistent to experimental results. Therefore, the DFT-PBE0-GIAO method is employed to predict the 31P chemical shift of 2 and 4 with 61.66ppm and 56.49ppm. (5)The increase of Fe-C*Fe-P delocalization and the decrease of Fe-P*Fe-C interaction raise the electron density of P nucleus in the binuclear complexes，so the 31P chemical shifts of binuclear complexes are smaller than that of mononuclear complex.
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Keywords:
- DFT(PBE0) /
- GIAO /
- metal-metal interaction /
- 31P chemical shifts
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