19电子配合物非线型M-C-O本质的密度泛函研究(M=Fe,Ru,Os)

DFT study on the origin of bent M—C—O of the 19-electron complexes(M=Fe,Ru,Os)

采用密度泛函理论方法,对一系列19电子铁族配位化合物CpM(CO)2L·进行了结构优化和能量计算.计算结果表明:配体L为羰基时,同族三金属Fe,Ru和Os配合物中都会出现一个弯曲的M—C—O,金属M的电子转移到CO上以满足18电子规则的特征;当L为磷配体时,Fe配合物中2个M—C—O都是线型的.而Ru和Os两者表现类似,可以存在2种不同的结构:第1种是2个M—C—O都是线型的;第2种是有一个线型M—C—O,而另一个M—C—O是弯曲的.理论计算得到的弯曲结构更稳定的结果和实验相符.配合物几何结构的差异可以通过三金属原子的电子构型、原子半径和电子转移得到解释.

Geometry optimization and energy calculation of a series of the 19 electionic iron group complexes CpM（CO）2L·are carried out at density functional theory（DFT）level.And computational results indicate that,Fe,Ru and Os will have one bent M—C—O in the complexes if ligand L is CO,displaying aproperty of electron transfer from M to L,to meet the 18-electron rule.If ligand PR3 exists,all two M—C—O are linear for iron while ruthenium and osmium complexes behave similar to each other,i.e.,two different structure are available：the first type has unbent M—C—O and the second configuration owns one bent and one unbent M—C—O.Theoretical investigation agrees well with experimental observation in that the bent structure is more stable than unbent one.The difference in the geometries of complexes can be explained by effects of electron configuration,atomic radius and electron transfer for Fe,Ru and Os atoms.