取代基和配体的负离子效应对(TPFC)Mn(V)O轴向配位作用的影响

Effects of Substituents and Anionic Ligands on Axial Coordination of (TPFC)Mn(V)O

  • 摘要: 采用密度泛函理论(DFT)的BP86方法对系列位取代的锰(Ⅴ)-氧咔咯((TPFC)MnⅤO)配合物与咪唑的轴向配位作用,以及无位取代的(TPFC)MnⅤO与轴向配体4-甲基咪唑和吡咯的轴向配位性质进行理论研究。计算结果显示位取代基吸电子性质和轴向配体负离子效应均能缩短配位键长并增大结合能,显著增强(TPFC)MnⅤO配合物轴向配位作用。通过自然键轨道(NBO)分析发现影响其轴向配位作用的主要因素是轴向配体上氮原子的孤对电子轨道LP(N)与锰原子的孤对电子轨道LP(Mn,4s)和锰氧反键轨道*(MnO)间的二级微扰稳定化能E(2),取代基吸电子效应和轴向配体负离子效应均能导致E(2)值增大,显著增强(TPFC)MnⅤO的轴向配位作用。

     

    Abstract: The axial coordination of a series of site substituted manganese(V) oxygen corrole complexes ((TPFC)MnVO) with imidazole and the non-substituted (TPFC)MnVO with 4-methyl imidazole and pyrrole were investigated using the density functional theory (DFT) with BP86 method. The calculation results show that the electron-withdrawing ability of the -substituents and the anionic effect of the axial ligand can both result in a short length of coordination bond and the strong binding energy, which significantly enhance the axial coordination interaction of the (TPFC)MnVO complex. The main factors affecting the axial coordination is the second order perturbation stabilization energies E(2) which including lone pair electron orbit of nitrogen on the axial ligand (LP(N)) to the lone pair electron orbital of manganese (LP(Mn,4S)) and to the anti bond orbital of manganese oxygen bond (*(MnO)) by the natural bond orbital (NBO) analysis, respectively. The axial coordination of (TPFC)MnVO is enhanced significantly by the strong electron-withdrawing ability of the substituents and the anionic axial ligands.

     

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