含μ_3－S平面型多核钼簇合物化学键性质研究

Study on the Chemical for Planar Multi-nuclear Molybdenum Cluster Compouns with Containing μ_3-S

采用量子化学的ＣＮＤＯ／２－ＬＭＯ方法计算，讨论以为基本结构单元通过μ＿３－Ｓ连结为平面型多核簇合物的化学键特性。这里以四核和六核平面簇合物为例。计算表明：这类平面型簇合物的μ＿３－Ｓ与三个金属组成的四中心键是较弱的，对于四核簇合物基本上是三个二中心双电子Ｍｏ－Ｓｃ键。而侧基桥硫原子轨道与金属ｄ原子轨道有较明显ｄ－ｐ共轭作用，有趣的是六核簇合物的金属键是由６个ｐ轨道共轭П键性质。

The chemical bond characterictic in one class of planar multi-nuclear cluster com-pounds having the core used for essential structure's unit is discussed in terms of the result ofmolcular orbital calculations using the CNDD/2-LMO method,for exampl planar tetranuclear clustercompound and hexanuclear cluster compound.The calculated results show that four-centred bond con-sisting of three skeletaI MO atoms and μ_3-S cap is a weaker. There is essentially the two-centred two-electron bond of three Mo-Sc in the four-centred cluster cumpound.But yet the atomic orbitals ofbridge sulphur atoms and d orbitals of metals form obvlously d-π conjugated effect.It is of interest tometal-metal bond for hexanuclear cluster compound to be of the nature of conjugated π bond with sixP-orbitals.