[Fe(H2O)m(OH)n]x配合物电子结构的理论研究

在B3PW91/6-31G(d, p)计算水平上，对铁离子配合物［Fe(H₂O)_m(OH)_n］^x(m+n=4; x=3+,2+,1+,0,1-)的5种可能构型进行优化计算，分析比较了优化结果的几何构型、电荷布居以及能量。计算结果表明：这5种配合物在理论上都有可能稳定存在，配体以氧原子与铁离子配位并形成四面体构型，有部分电荷从氧原子转移到铁离子，OH^-与Fe³⁺的配位作用较强。铁离子的d电子以高自旋的形式排布，形成开壳层的电子结构，其中Fe(OH)₄^-的d电子最难以发生跃迁。比较具有相同数量Fe³⁺、H₂O和OH^-的［Fe(H₂O)_m(OH)_n+jH₂O+kOH^-］体系的能量，发现随着［Fe(H₂O)_m(OH)_n］^x中OH^-数量的增加，H₂O数量的减少，体系的能量逐渐降低。所以，［Fe(OH)₄^-+6H₂O+2OH^-］体系最稳定，与布居分析中OH^-与Fe³⁺的配位作用较强的结果相一致。

Theoretical study of the electronic structures of [Fe(H2O)m(OH)n]x

The structures of Fe(H2O)m(OH)n]x(m n=4;x=3 ,2 ,1 ,0,1-) have been optimized by the Density Functional Theory(DFT) method at the B3PW91/6-31G(d,p) level.The geometric parameters,charge distribution and total energies of the complexes have been analyzed.The computational results show that all five structures are energetically stable.The structures involve Fe-O tetrahedra in which four oxygen atoms are directly bonded to Fe3 with charge transfer from oxygen atoms to Fe3 .The complexation of OH-with Fe3 is stronger than that of H2O.The complexes are high spin,and the electronic transition of Fe(OH)-4 requires the largest amount of energy.The total energy of Fe(H2O)m(OH)n jH2O kOH-](m j=6;n k=6) systems with the same number of Fe3 ,H2O and OH groups decreases gradually with increasing number of coordinated OH-groups.Therefore,Fe(OH)-4 6H2O 2OH-] is energetically most stable,which is consistent with the conclusion that the complexation of OH-with Fe3 is stronger than that of H2O according to population analysis.