我国变价稀土化学与物理的研究现状

稀土元素的主体一镧系元素原子的电子层结构为[Xe]4f~(0-14)5d~(0-1)6s~2。当其失去两个6s和一个5d或4f电子后,形成了最常见的Ln~(3+),其中La~(3+),Gd~(3+)及Lu~(3+)的4f亚层分别为全

SYNTHESIS AND CRYSTAL-STRUCTURE OF (C9H7GDCL2.3THF)THF

The indenylpdolinium dichloride tristetrahydrofuranate (C9H7GdCl2.3THF)THF was prepared and its crystal structure (monoclinic space group P2(1)) determined by X-ray diffraction. In C9H7GdCl2.3THF, Gd, O(1), O(2), O(3) and the centroid of the five-membered indenyl ring form a plane, and Cl(1) and Cl(2) are located at two opposite sides of the plane to give a pseudo-octahedron. The coordination number of Gd is eight.

SOLID-STATE C-13 NMR-STUDIES ON THE CONDENSATION AND SULFONATION OF FURFURYL ALCOHOL AND TRIS (2-HYDROXYETHYL) ISOCYANURATE

The condensation and sulfonation of furfuryl alcohol (FA) and FA with tris (2-hydroxyethyl) isocyanurate (THEIC) and the crosslinking product structures were studied by means of solid-state C-13 NMR. The reaction of formalin with FA linear oligomer terminated by 2-methyl furan took place in the presence of the phase transfer catalyst (C4H9)4N+I-. The reaction of the terminated oligomer with a large amount of sulfuric acid as well as the former reaction was examined. The effects of some main reaction conditions on the crosslinking condensation and sulfonation were also discussed.

碳-13核磁共振定量测定萄葡糖及果糖的含量

本文利用~(13)C-NMR方法测量由葡萄糖通过葡萄糖异构酶的作用,在不同的条件下,在转化为果糖的过程中葡萄糖和果糖的相对含量。同时~(13)C-NMR技术也是直接测定各种构型糖含量的有效方法。实验结果表明,Gd-DPTA弛予试剂能够使自旋-晶格弛豫时间(T1)缩短。同时对NOE效应的消除也作了描述。本法测定的相对误差低于±0.5％。

苯基稀土钆配合物的成键性质研究

苯基稀土钆配合物具有Ln-Cσ键,由于这类配合物不稳定且分离困难,故其研究工作开展得很少~[1,2],其电子结构的研究尚未见报道.最近,我们合成了新型的苯基稀土配合物C_6H_5LnCl_2·nTHF(Ln=Pr、Sm、Gd,n=3,4)并测定了其晶体结构~[3],本文报道了苯基稀土钆配合物的电子结构和成键性质,并与中性苯稀土配合物的成键性质~[4]进行了比较.

稀土三氟乙酸络合物的快原子轰击质谱研究

本文首次报道Ln(OOCCF_3)_3(Ln=Pr、Nd、Sm、Eu、Gd、Tb、Ho、Er、Tm、Yb、Lu在甘油(G)中的正负离子FAB谱、总结了其离子特征。通过亚稳分析、探讨了某些离子的碎裂方式,提出了Ln(Ⅱ)→Ln(Ⅰ)可能的还原变价机制。

LnVO_4:Eu发光中有关的化学因素

本文讨论了LnVO_4:Eu(Ln_(0.9)Eu_(0.1)VO_4,Ln=La~(3+)、Gd~(3+)、Y~(3+)、Sc'+和Lu_(3+))多晶粉末中Eu~(3+)离子~5D_0→~7F_2电偶跃迁(618.4nm)发光与化学组成、晶体结构和R—O键强之间的变化规律。

稀土硼酸盐中影响Dy~(3+)发光的因素

60年代初对ABO_3型稀土硼酸盐的合成、结构和性质的研究已有报道。80年代侧重稀土和金属离子硼酸盐发光规律的研究。 Srivastava曾对GdBO_3中pr~(3+)的光谱及Gd~(3+)对Pr~(3+)的敏化、郭风瑜,李有谟

[Li(THF)_4][GdCl_4(THF)_2]的晶体结构

氯化钆与对-甲基苯基锂在四氢呋喃中反应得到产物之一为[Li(THF)_4][GdCl_4-(THF)_2],(M_r=738.2),在-70℃下进行X-射线衍射研究。其晶体属单斜晶系,P2/n空间群。晶体学参数为a=13.263(2),b=8.474(1),c=14.961(0);β=99.72(1)°,V=1657.23(?)~3,Z=2,D_c=1.48g/cm~3,F(000)=750,μ_c=24.2cm~(-1),最终偏离子为R=0.0614。研究结果表明,本题晶体是离子型晶体,围绕Gd~(3+)的四个Cl~-离子和两个THF分子的氧原子构成畸变的八面体。Li~+周围的四个THF分子的氧原子构成一个近似的四面体。

PREPARATION AND MOLECULAR-STRUCTURE OF METHYLBIS(TERT-BUTYLCYCLOPENTADIENYL)NEODYMIUM AND METHYLBIS(TERT-BUTYLCYCLOPENTADIENYL)GADOLINIUM

Bis(t-butylcyclopentadienyl)lanthanide chloride (Ln = Nd or Gd) reacts with one equivalent of methyllithium in ether/tetrahydrofuran to give the complex [(C5H4tBu)2LnCH3]2 (Ln = Nd or Gd). The structure of [(C5H4tBu)2NdCH3]2 has been determined by X-ray analysis. The crystals are monoclinic of space group Cm with a = 9.538(2), b = 23.298(4), c = 9.505(3) angstrom, beta = 119.53(2)-degrees, V = 1828.0(7) angstrom 3, D(calc.) = 1.458 g/cm3 and Z = 2 for the dimer. The two (C5H4tBu)2Nd units in the dimer are connected by asymmetrical methyl bridges with independent Nd-C bond lengths of 2.70(2) and 2.53(2) angstrom and Nd-C-Nd angles of 94.7(9) and 87.3(6)-degrees.

THE SYNTHESES OF THE COMPLEXES (ETA-5-C5H5)LN(ETA-8-C8H8).NTHF AND (ETA-5-C9H7)LN(ETA-8-C8H8).2THF AND THE CRYSTAL-STRUCTURE DETERMINATION OF (ETA-5-C5H5)PR(ETA-8-C8H8).2THF AND (ETA-5-C9H7)PR(ETA-8-C8H8).2THF

LnCL3 reacts with NaC5H5 and K2C8H8 to yield the complexes (eta-5-C5H5)Ln(eta-8-C8H8).nTHF (Ln = Pr, Nd, n = 2; Ln = Gd, n = 1) and LnCl3 reacts with KC9H7 and K2C8H8 to yield the complexes (eta-5-C9H7)Ln(eta-8-C8H8).2THF (Ln = Pr, Nd; eta-5-C9H7 = indenyl); crystallography reveals (eta-5-C5H5)Pr(eta-8-C8H8).2THF and (eta-5-C9H7)Pr(eta-8-C8H8).2THF not to possess the parallel ring sandwich structure.

SYNTHESES OF BIS(TERT-BUTYLCYCLOPENTADIENYL)LANTHANOID CHLORIDE COMPLEXES AND CRYSTAL-STRUCTURES OF BIS(TERT-BUTYLCYCLOPENTADIENYL)CHLORO(BISTETRAHYDROFURAN)-PRASEODYMIUM AND BIS(TERT-BUTYLCYCLOPENTADIENYL)-CHLOROTETRAHYDROFURANYTTERBIUM

Reaction of lanthanoid trichloride with two equivalents of sodium t-butylcyclopentadienide in tetrahydrofuran affords bis(t-butylcyclopentadienyl)lanthanoid chloride complexes (t-BuCp)2LnCl. nTHF (Ln = Pr, Nd, n = 2; Ln = Gd, Yb, n = 1). The compound (t-BuCp)2PrCl.2THF (1) crystallizes from THF in monoclinic space group P2(1)/c with unit cell dimensions a = 15.080(3), b = 8.855(2), c = 21.196(5) angstrom, beta = 110.34(2)degrees, V = 2653.9 angstrom-3 and D(calcd) = 1.41 g/cm3 for Z = 4. The central metal Pr is coordinated to two t-BuCp ring centroids, one chlorine atom and two THF forming a distorted trigonal bipyramid. The crystal of (t-BuCp)2YbCl.THF (2) belongs to the monoclinic crystal system, space group P2(1)/n with a = 7.726(1), b = 12.554(2), c = 23.200(6) angstrom, beta = 97.77(2)degrees, V = 2229.56 angstrom-3, D(calcd) = 1.50 g/cm3 and Z = 4. The t-BuCp ring centroids, the chlorine atom and the oxygen atom of the THF describe a distorted tetrahedron around the central ion of ytterbium.

THERMODYNAMICS OF COMPLEXATION OF RARE EARTHS BY L-METHIONINE

The protonation constant of the ligand and stability constants of it complexes with rare earths have been determined by potentiometric titration at 25 degrees C and ionic strength mu=0.15 mol - L-1. The results indicate that rare earth elements can form 1:1 complexes with L methionine. There is an apparent "tetrad effect" in this system. Shift of the yttrium position to the vicinity of Gd can he explained by the different polarisation between the Ln(3+) and the ligand. The enthalpy changed (Lambda H-101) of the coordination reaction as represented by the reaction (M + L (sic) ML) here been measured by calorimetric titration, where M and L. denote are eartus and L-Mer respectively. The Lambda G(101) and Delta S-101 of these reaction have been calculated by using Gibbs' equation, Furthermore, the stability of rare earth complexes with L-Met has been compared with that of Ca3+ Zn3+, Fe2+, Fe3+ complexes with L-Met.

三价稀土离子半径对LnBa_2Cu_3O_(7-δ)化合物的结构及超导电性的影响

合成了LnBa_2Cu_3O_(7-δ)(Ln=La,Nd,Sm,Eu,Gd,Dy,Er,Yb)系列化合物,通过XRD,XPS第手段研究了Ln(Ⅲ)离子半径对LnBa_2Cu_3O_(7-δ)化合物的结构及超导性的影响。Ln(Ⅲ)离子的固有磁矩(或4f电子)并不影响LnBa_2Cu_3O_(7-δ)化合物的超导电性,但是,Ln(Ⅲ)离子的大小却显著影响LnBa_2Cu_3O_(7-δ)化合物的微观结构(尤其是对Cu_2周围环境的影响)。XPS结果表明:尽管Cu_(2P3)/2的峰未劈裂,但Cu的结合能随Ln原子序数增加而明显增加,我们认为Cu_1和Cu_2都具有变价,介于2—3之间。

Ce_xGd_yTb_(1-x-y)P_5O_(14)晶体生长及其光谱

采用蒸发溶液法从磷酸溶液中生长出一系列Ce_xGd_yTb_(1-x-y)P_5O_(14)晶体.测定了它们的结构.它们属于单斜晶系,空间群P2_(1/c).测定了Ce_(0.9)Gd_(0.1)P_5O_(14)、Ce_(0.9)Tb_(0.1)P_5O_(14)和La_(0.8)Gd_(0.1)Tb_(0.1)P_5O_(14)等晶体的光谱.首次观察到,将Gd加入Ce_xTb_(1-x)P_5O_(14)晶体中形成.Ce_xGd_yTb_(1-x-y)P_5O_(14)时阻碍了Ce~(3+)→Tb~(3+)的能量传递,导致Ce~(3+)的发射峰增强,Tb~(3+)的~5D_4—~F_J发射峰减弱、而~5D_3—~7F_J发射峰增强.