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采用从头计算方法和密度泛函理论方法,对三(五甲基环戊二烯基)稀土金属配合物(C5Me5)3Ln(Ln=Sc,Y,La)的几何结构、电子结构以及Ln-C5Me5之间的结合能进行了研究.(C5Me5)3Ln的电子结构符合过渡金属配合物“18电子规则”的描述,因而具有较好的稳定性.Ln原子的(n-1)d、ns轨道能够与C5Me5的π轨道较好的重叠并组成强成键轨道.研究发现(C5R5)3Ln(R=H,Me)的几何结构受到“Ln-C5R5成键效应”和“C5R5-C5R5位阻效应”两个相反因素的影响,其稳定性则受到“Ln原子半径-(C5R5)3孔径尺寸”匹配关系的制约.在C5R5上引入特定的取代基后可以从轨道能级、金属原子-配体距离、配体-配体距离等多方面直接或间接的影响Ln-C5R5间的成键强度,进而实现对(C5R5)3Ln稳定性和反应活性的控制.
The geometry, electronic structure and Ln-C5Me5 of L5 (C5Me5) 3Ln (Ln = Sc, Y, La) were investigated by ab initio method and density functional theory (C5Me5) 3Ln has the same electron structure as that of the transition metal complex “18Electronic rule ”, so it has better stability. (N-1) d, ns The orbitals can overlap well with the π orbitals of C5Me5 and form strong orbitals. The geometry of (C5R5) 3Ln (R = H, Me) has been studied by the “Ln-C5R5” bonding effect and the “C5R5- C5R5 steric effect ”of the two opposite factors, its stability is subject to “ Ln atomic radius - (C5R5) 3 pore size ”after the introduction of specific substituents on the C5R5 from the orbital energy Level, metal atom-ligand distance, ligand-ligand distance and other aspects directly or indirectly affect the bond strength between Ln-C5R5, so as to achieve the control of the stability and reactivity of (C5R5) 3Ln.