三(五甲基环戊二烯基)稀土金属配合物(C_5Me_5)_3Ln(Ln=Sc,Y,La)的量子化学理论研究  

Theoretical Investigations on Tris(pentamethylcyclopentadienyl) Rare Earth Metal Complexes (C_5Me_5)_3Ln (Ln=Sc, Y, La)

作　　者：仇毅翔[1] 王曙光[1] 

机构地区：[1]上海交通大学化学化工学院,上海200240

出　　处：《化学学报》2012年第18期1930-1938,共9页Acta Chimica Sinica

基　　金：国家自然科学基金(No.20973109)资助~~

摘　　要：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 molecular geometric and electronic structures of tris（pentamethylcyclopentadienyl） rare earth metal complexes（C5Me5）3Ln（Ln=Sc,Y,La） were investigated by means of ab initio HF,MP2 and density functional theory（DFT） methods.The bonding energies of Ln-C5Me5 were also analyzed on the basis of calculations.To study the effect of the exchange-correlation（XC） functional on the structural parameters and bonding energies,LDA（Xα,SVWN3,SVWN5）,GGA（BP86,BLYP）,meta-GGA（TPSS） and hybrid（B3LYP,PBE0,TPSSh,M06,M06-HF,M06-2X） functionals have been used.Calculations were carried out with the TZVPP basis sets.The geometry structural parameters from the different methods were compared to the experimental values.The Ln—C distance of（C5Me5）3Ln shows a dramatic reduction of about 15 pm from HF to MP2 level.These differences demonstrates the importance of electron correlation on the Ln-C5Me5 bonds.In（C5Me5）3Ln complexes,the geometric parameters differ much for different DFT exchange-correlation functional.For the Ln—C bond length,the theoretical values closest to the experiment were the M06-2X and M06 methods,with the deviation of only 1.2 and 2.5 pm,respectively.Thus,the M06-2X methods appear to be the most reliable for predicting the molecular structures of（C5Me5）3Ln.The studies of the electronic structures showed that the（C5Me5）3Ln satisfied the 18-electron rule,so these complexes had high stability.The（n-1）d and ns orbitals of Ln atom had a better overlap with the π orbitals of C5Me5.Our calculations revealed that the geometries of（C5R5）3Ln（R=H,Me） were influenced significantly by the ＂Ln-C5R5 bonding effect＂ and ＂C5R5-C5R5 steric effect＂,while the thermal stabilities were influenced by whether atomic radius of Ln was suitable for the ring size of（C5R5）3.Therefore,the introduction of specific substituents into C5R5 could affect the π orbital energies,Ln-C5R5 distance and C5R5-C5R5 distance,and then control the Ln-C5R5 bonding strength and stability

关 键 词：三茂基稀土金属配合物 从头计算 密度泛函理论 电子结构 金属-配体结合能 

分 类 号：O627.3[理学—有机化学]