(μ-L1)(μ-L2)十羰基合三锇电子光谱的含时从头计算

用从头计算(ab initio)方法,在HF/CEP-4G水平上,全优化计算了Os3(CO)10(μ-L1)(μ-L2)L1,L2=H,Cl,Br,I]簇合物的的分子几何构型,在此基础上对这些簇合物的前线轨道进行了讨论,发现对于M-M键,p轨道虽有贡献,但以s,d轨道的贡献为主,同时从Cl→I,随着桥配体原子序的增大,Os3(CO)10(μ-L)2类簇合物的HOMO与NHOMO轨道能量依次升高,而Os3(CO)10(μ-H)(μ-L)类簇合物只有HOMO轨道能量依次升高,而Os3(CO)10(μ-L)2类簇合物的LUMO与HOMO的能量差△εL-H及LUMO与NHOMO的能量差△εL-NH都依次变小,可以预示,簇合物的电子光谱基谱带将红移.用TDHF计算了这些簇合物的电子吸收光谱.计算结构表明,簇合物Os3(CO)10(μ-H)2(I)的跃迁主要为π→σ*和σ→σ*,对于其他几个簇合物Os3(CO)10(μ-H)(μ-L)L=Cl,Br,I]和Os3(CO)10(μ-L)2L=Cl,Br],电子吸收峰主要都发生在σ→σ*的跃迁.从Cl→I,随着桥配体原子序的增大,簇合物的电子光谱基谱带红移,且光谱线强度逐渐减弱.

TDHF Study of Electronic Absorption Spectrum of (μ-L1) (μ-L2) -Decacarbonyl Triosmium

Ab initio method was used to optimize the molecular geometry for a series of clusters (mu-L1) (mu-L2)- decacarbonyltri-osmium L1, L2 = H, Cl, Br, I] at HF/CEP-4G level. The related chemical properties of clusters, in particular, the regularities of the bridge halogen effects on spectroscopic properties and bonding properties were discussed. The calculation results of the frontier molecular orbital showed that M-M bonds were mainly composed of s and d atomic orbitals. From Cl to I, with the atom number of bridge ligand increasing, HOMO and NHOMO orbitals on the Os3(CO)10 (mu-L)2 clusters and HOMO on the Os3 (CO)10 (mu-H) (mu-L) clusters become higher, while deltaepsilonL-H and deltaepsilon-NH energies become lower, so the authors predicted that the electronic absorption bands of clusters are shifted to infrared region. Excited states of clusters calculated with TDHF show that the transition of cluster Os3(CO)10 (mu-H)2 (I) is mainly 7 --> sigma* and sigma --> sigma*, while the electronic absorption of other clusters Os3 (CO)10 (mu-H) (mu-L) L = Cl, Br, I] and Os3(CO)10 (mu-L)2 -L = Cl, Br] is mainly from sigma --> sigma* transition. From Cl to I, with the atom number of bridge ligand increasing, the electronic absorption band of cluster is shifted to infrared region, and also the absorption becomes weaker.