稀土夹心化合物的SCF-Xα-SW研究 Ⅲ.(Cp_2YbCl)_2和(Cp_2ErH)_2

SCF-Xα-SW Calculations on Lanthanide Metallocencs Ⅲ. (Cp_2YbCl)_2 and (Cp_2ErH)_2

用SCF-Xα-SW方法非相对论和相对论方案计算了稀土桥键夹心化合物(Cp_2.YbCl)_2和(Cp_2ErH)_2能级、轨道等值图形、布居数等的研究表明,(Cp_2YbCl)_2和(Cp_2ErH)_2的共价键比Cp_2Yb和 Cp_2YbC_2H_2强而与Cp_3Sm和 LnF_3相近,证实了三价稀土化合物共价键比二价化合物强;桥键氢原子较小的原子半径和价轨道单位相性质,使氢桥化合物(Cp_2ErH)_2形成比氯桥化合物(Cp_2YbCl)_2更强的共价键;非相对论和相对论计算能级结构、价轨道成分、成键图象等方面的差异,表明了研究重稀土化合物考虑相对论效应的必要性.

SCF-Xα-SW calculations are carried out on lanthanide bridge metallocenes: (Cp2YbCl)2 and (Cp2ErH)2, both of the nonrelativistic and relativistic schemes have been tried. It is shown that the bonds of (Cp2YbCl)2 and (Cp2ErH)2 are more covalent in character than those of Cp2Yb and Cp2YbC2H2 but similar to those of Cp3Sm and LnF3 from discussing energy level sequences, populations and contour maps. It find support that three valence Ln compounds are more covalent in character than two valence Ln ones. Because H atoms at the bridge have smaller atomic radius and the valent orbit with single phase, the covalent bonding of (Cp2ErH)2 with H bridge is stronger than that of (Cp2YbCl)2 with Cl bridge. There are some obvious differences in energy level sequences, valent orbital compositions and bonding pictures between the two schemes, which reveals that the relativistic scheme is necessary to obtain reliable results for heavy lanthanide compounds.