Roussin红盐和Roussin黑盐的电子结构

Roussin黑盐簇阴离子及其"元件化合物"Roussin红盐簇阴离子,是固氮酶活性中心福州模型I(网兜状原子簇模型)的模型物.本文用闭壳层CNDO/2(S,D方案)法计算了它们的电子结构.根据计算所得的Mulliken重叠集居,电荷密度,分子轨道能量和轨道特征等数据,对成键性质进行了分析,得出如下主要结论:两种簇阴离子骨架电子的非定域性都比较强,桥硫原子Sb在由红盐形成黑盐的电子转移过程中起施主作用,两种簇阴离子中都存在M-M键,强度与M-Sb键相近,其主要贡献都来源于金属的s,pz,dz2轨道与硫原子的s,pz轨道之间的σ作用,金属d轨道的π作用对整个骨架的成键贡献很小.

The electronic structures of red roussinate and black roussinate

The electronic structures of the black Roussinate anion, the string bag cluster model of the active center of nitrogenase, and its cluster fragments, the red Roussinate dianion, were calculated using the close shell CNDO/2 (S, D scheme) method. From the analyses of the bonding properties on the basis of Muelliken populations, charge densities, MO energies, and MO characters, the following results were revealed. An intensive electron delocalization was found in these 2 clusters. In the process of electronic transfer from the red Roussinate to the black Roussinate, the bridging S atom (Sb) was the electron donor. There existed a certain degree of M-M (where M is metal) bonding in these 2 clusters with the strength of the M-M bond near to that of M-Sb bond; the chief contribution to these bonds was the interaction between the s, p, and dz2 orbitals on the metal atoms and the s and pz orbitals on the S atoms. The contribution of the p interaction between the d orbitals on the metal atoms to the bonding of the cluster skeleton is quite small.