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采用密度泛函理论B3LYP方法在6-31G(d)基组水平下对氯化铁(+3)卟啉与氧气分子形成的体系进行了研究,得到了几何构型,电子性质及分子轨道结构等相关数据。对两个体系不同自旋状态下的几何构型参数和电子性质对比发现:受体系立体构型对称性的影响,在两个体系中凡是与卟啉环上N原子相关的几何参数及电子性质均呈现出相同规律性。又采用密度泛函理论UB3LYP/6-311G~*//UB3LYP/6-31G~*方法对这两个体系不同自旋状态下的能量进行了计算,分析表明自旋多重度越高体系越稳定。然后分别分析了两个体系在最稳定自旋状态下的分子轨道占据情况及中心Fe原子最外层3d轨道的电子分布情况,结果表明Fe原子的3d_22和3d_(xz)/3d_(yz)与氧气分子的单占据反键轨道HOMOπ~*2p_x/π~*2p_y之间存在相互作用,这种相互作用引起铁卟啉环与O_2分子间的电子转移并使O_2活化。然而,根据分析在通常状态下铁卟啉对O_2分子的活化作用是微弱的。
The density functional theory (B3LYP) method was used to study the formation of iron (+3) porphyrin and oxygen molecules at 6-31G (d) basis level. The geometrical configuration, electronic properties and molecular orbital structure Related data. The comparison of geometric configuration parameters and electronic properties under different spin states of the two systems reveals that the geometrical parameters and electronic properties related to the N atom on the porphyrin ring in the two systems are affected by the symmetry of the stereospecific configuration of the system All showed the same regularity. The energy of the two systems under different spin states was also calculated using the density functional theory UB3LYP / 6-311G ~ * // UB3LYP / 6-31G * method. The analysis shows that the higher the spin multiplicity, the more stable the system . Then we analyze the orbital occupancy of the two systems under the most stable spin state and the electron distribution of the 3d outermost orbitals of the Fe atoms. The results show that the 3d_22 and 3d_ (xz) / 3d_ (yz) Oxygen molecules occupy an antibonding orbital between HOMOπ ~ * 2p_x / π ~ * 2p_y, which interacts with each other to cause electron transfer between iron porphyrin ring and O_2 molecule and activate O_2. However, according to the analysis, the activation of O 2 molecules by ferroporphyrin is weak under normal conditions.