Reaction of [(ButCp)2Er(μ-Cl)]2 with ButLi in 1 : 1 molar ratio in THF at -78°C; after work-up, afforded the trimetallic erbium tetrahydride complex [Li(THF)4] [(Bu t Cp)2 Er(μ-H) 3(μ3-H)] (1) by ββ-hydrogen elimination reaction. Crystal structure determination reveals that complex 1 has discrete ion pair structure. The anion is composed of three (ButCp)2Er units to form a triangle array connected by three bridged hydrogen atoms, and the fourth hydrogen atom coordinated to three Er3+ ions. The coordination number for each Er3+ ion is 9.

[(Bu^tCp)2Er(μ-Cl)]2(Bu^tCp=叔丁基环戊二烯基)与叔丁基锂(Bu^tLi)在四氢呋喃(THF)中按1：1的摩尔比于-78℃反应，分离得到了经β-氢消除反应形成的三核四氢稀土金属有机化合物[Li(THF)4][{(Bu^tCp)2Er(μ-H)}3(μ3-H)](1)．晶体结构测定表明配合物1具有离子对结构，阴离子部分由3个(Bu^tCp)2Er单元组成，呈三角形排列，三角形的三边通过3个氢桥连接起来．另外有一个氢位于三角形内，以μ3-H方式和3个Er^3+离子配位，每个Er^3+离子的配位数为9.

Reaction of [((BuCp)-Cp-t)(2)Er(mu-Cl)](2) with (BuLi)-Li-t in 1 : 1 molar ratio in THF at -78degreesC, after work-up, afforded the trimetallic erbium tetrahydride complex [Li(THF)(4)] [{((BuCp)-Cp-t)(2)Er(mu-H)}(3)(mu(3)-H)] (1) by beta-hydrogen elimination reaction. Crystal structure determination reveals that complex 1 has discrete ion pair structure. The anion is composed of three ((BuCp)-Cp-t)(2)Er units to form a triangle array connected by three bridged hydrogen atoms, and the fourth hydrogen atom coordinated to three Er3+ ions. The coordination number for each Er3+ ion is 9.

The reaction of anhydrous PrCl3 with Na(C9H7) in 1:2 mole ratioin THF gives [(C9H7)2PrCl(THF)]2 1.1 crystallized in monoclinic system, space group P21c with a = 7.808(2), b = 17.796(6), c = 14.070(4) Å, β = 93.97(2)°, V = 19.50.3(9) Å3, Dcalcd = 1.63 g/cm3 and Z = 2. Each Pr iron is surrounded by two indenyl, two Cl and one THF in a roughly trigonal bipyramid arrangement with average PrC(ring) and PrCl distance of 2.81 and 2.84 Å. The reaction of LaCl3 with Na(C9H7) in 1:3 mole ratio gives (C9 H7)3LaTHF 2 which crystallizes in the monoclinic space group P21a with unit cell constants a = 21.871(8), b = 10.585(3), c = 23.652(7) Å, β = 114.62(2)°, V = 4977.9 Å3 and Z = 8.