过渡金属异核原子簇化学键研究 2.IB-Ⅷ,IB-ⅥB族金属四核原子簇电子结构研究

Quantum Chemical Research for Heterometal Four - nuclear Cluster Compounds of Transition Metal 2. Electronic Structure and Energy Band of Four - nuclear Cluster Formed from IB - VIII, IB - VIB Elements

我们选择了14个IB-Ⅷ,IB-ⅥB族异金属四核簇合物,用DV-X_a方法研究它们的成键规律、配体效应及能级变化.计算表明:它们按构型可分为三类:三角锥、蝶型、平面四边形.金属簇骼轨道分别为6个、5个、4个,稳定性也依次降低.文中还讨论了三苯基膦等配体在合成IB簇合物中的作用和异核簇中d能带的变化对吸附的影响.

We have chosen 14 mixed - metal, four - nulear cluster compounds formed from IB-VIII or IB elements to study their bonding regularity, liqand effect and energy change using DV -Xa method. Quantum chemical calculation show that they may be classified as three types: the first cluster core presents a triangular pyramid, there are 6 metal skeleton orbitals and is more stable one. For second cluster, its metal skeleton likes a butterfly (double bond at body and single bond at wing), IB atom preserves valence electrons of itself as far as possible and VIII atom make major contribution of charges. In third cluster, the metal bond is strong between two IB atoms and is weak between IB- VIII or IB- VIB atoms, so cluster is more unstable one. We have also found that the triphenyl phosphine liqand is a better electronic adjuster for cluster syntheses -unnecessory. Because emergy of IB metal is difference with VIII or VIB metal, energy of mixed -metal cluster changes clearly, so cluster reaction activity and catalysis selectivity change,too.