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本文采用CNDO/2-SD方法计算了二铁氧还盐及四铁氧还盐的电子结构.与Roussin红盐及Roussin黑盐的电子结构比较,相似之处为:在铁局部对称性为四面体的簇合物中,Fe—Fe间相互作用主要由铁的s,p电子的σ贡献产生,金属d轨道的π相互作用在占有轨道区间同时具有成键和反键贡献,因而对骨架的形成几乎无贡献.骨架μ_2-S桥含有孤对电子,有形成μ_3-S桥的可能,但以桥硫孤对电子贡献为主的轨道都不是前线轨道.不同之处在于端基为SH的簇合物骨架电子的非定域性较端基为NO时更强.二核簇合物Fe与端基SH的成键能力比与NO的小,因而在自兜反应中容易失去端基SH而形成封闭型结构.
In this paper, the electronic structure of di-iron oxide and tetra-iron oxide salt was calculated by CNDO / 2-SD method.Compared with the electronic structure of Roussin red salt and Roussin black salt, the similarities are as follows: the local symmetry of iron is four sides In the bulk cluster, the interaction between Fe-Fe is mainly caused by the σ contribution of the s and p electrons of the iron. The π interaction of the metal d orbitals has both the bonding and the antibonding contributions in the occupied orbital region, The skeleton μ_2-S bridge contains lone pairs of electrons, which may form the μ_3-S bridge, but the orbitals which are mainly composed of bridged lone pairs are not frontier orbits, except that the terminal group is SH The delocalization of the cluster backbone electron is stronger than that of the terminal group NO.Furthermore, the bonding ability between Fe and terminal SH of Fe cluster is smaller than that of NO, so the terminal group SH is easily lost in the self-pocket reaction The formation of a closed structure.