S_(2)N_(2)环和H_(4)B_(2)N_(3)^(-)环的过渡金属配合物的稳定性比较的理论研究

A THEORETICAL COMPARAISON STUDY ON STABILITIES OF TRANSITION METAL COMPLEXES OF S_(2)N_(2) AND H_(4)B_(2)N_(3)^(-) RINGS

本文从推广 Hüekcl 计算的结果,提出了三个衡量稳定性的指标,对典型的硫氮环和硼氮环:S_2N_2和 H_4B_2N_3^-的过渡金属配合物(σ配合物和夹心配合物)的稳定性作了比较,并用定性分子轨道理论对配合物的电子结构和化学成键作用作了讨论。结果表明,对于 H_4B_2N_3^-环,σ配合物比π配合物稳定,但S_2N_2环则相反,σ配合物不如π配合物稳定。从π重迭布居和电荷分布分析,活化 S_2N_2环上的硫原子应是合成夹心配合物的重要步骤。

In this paper three stability indexes are suggested from the results of extended Hückel calculations to compare the stabilities of transition metal complexes (σ-and sandwich complexes) of typical sulfur-nitrogen ring S_2N_2 and Boron-nitrogen ring H_4B_2N_3^-.Qualitative MO theory is used to discuss the electronic structure and chemical bonding in these complexes.It is predicated that σ-complexes are more stable than π-complexes for H_4B_2N_3^- ring,but for S_2N_2 ring its σ-complexes are not as stable as π-complexes.It is also predicated that from analysing overlap populations and charge distributions,activating the sulfur atoms on S_2N_2 ring should be a important step of synthesizing its sandwich complexes.