ANALYSIS OF ANGULAR OVERLAP PARAMETERS FOR EU3+ - LN2O2S (LN = LU, Y, GD, LA) CRYSTAL SERIES

The angular overlap model (AOM) is applied to 4f6 electron systems. The crystal field parameters are interpreted and covalency between 4f electrons and ligands is investigated based on the experimental energy levels. For Eu3+:Ln2O2S (Ln = Lu, Y, Gd, La) crystal series, we adopt two computational schemes. First of all, we assume that the distances to all ligands are equal, and then the distances to all ligands are divided into two groups, namely, oxygens as one group, sulfurs as the other. Of course, much information about covalency will be obtained from the latter case. Obviously, our results show that the covalency of Ln-O bonding is stronger than that of Ln-S bonding in line with much shorter bondlength for the former than that for the latter. The two schemes yield the same results, that is, for sigma and pi bonding, ligands are strong donors as well as sigma, pi effects are dominant over delta, phi effects.

SYNTHESES OF METHYLCYCLOPENTADIENYL DERIVATIVES OF LANTHANIDES (LN = LA-ND) AND CRYSTAL-STRUCTURES OF [(THF)2LI(MU-CL)2]2[MECPND(THF)] AND [LI(DME)3][MECPLA(NPH2)3]

The reaction of LnCl3.2LiCl with 1 equiv of MeCpNa in THF gives the complexes [(THF)2Li(mu-Cl)2]2[MeCpLn(THF)] (Ln = Nd (1), La (2)) in good yield. These precursors react further with 2 equiv of LiNPh2 to produce the new complexes [Li(DME)3][MeCpLn(NPh2)3] (Ln = La (3), Pr (4), Nd (5)). They have been characterized by elemental analyses and IR and NMR spectra, as well as by structural analyses of 1 and 3. The chloride 1 crystallizes in the monoclinic space group P2(1)/n (No. 14) with a = 12.130 (5) angstrom, b = 17.343 (5) angstrom, c = 17.016 (5) angstrom, beta = 108.54 (3)-degrees, V = 3393.87 angstrom3, Z = 4, and D(c) = 1.45 g/cm3. Least-squares refinement led to a final R value of 0.051 (I greater-than-or-equal-to 3-sigma(I(o))) for 2004 independent reflections. Complex 3 crystallizes in the monoclinic space group P2(1)/c (No. 14) with a = 18.335 (6) angstrom, b = 16.576 (5) angstrom, c = 17.461 (6) angstrom, beta = 96.04 (3)-degrees, V = 5277.17 angstrom3, D(c) = 1.26 g/cm3, Z = 4, and R = 0.057 (I greater-than-or-equal-to 2.5-sigma(I(o))) for 3378 reflections. The structure of 3 consists of discrete ion pairs [Li(DME)3]+ and [MeCpLa(NPh2)3]- with average La-N and La-C(ring) distances of 2.459 (8) and 2.84 (1) angstrom, respectively.

LnP_5O_(14)(Ln=La—Tb)晶体的相变和缺陷

本文用X射线衍射方法研究 LnP_5O_(14)(Ln=La,Pr,Nd,Sm,Tb)晶体相变表明,相变是晶轴 c 和α夹角β随温度升高逐渐减小的过程,也就是晶体的畸变角δ随温度下降而增加。相变温度随稀土离子半径由 La 到 Tb 减小呈线性增加,最后讨论了晶体缺陷随温度的变化关系。

(η~5-C_5H_5)Ln(η~8-C_8H_8)(THF)_n(Ln=Pr,Nd,Gd)的合成及(η~5-C_5H_5)Pr(η~8-C_8H_8)(THF)_2的晶体结构

自1969年首次报道稀土环辛四烯基化合物Eu(C_8H_8)和Yb(C_8H_8)的合成以来,相继合成K[Ln(C_8H_8)_2],[Ln(C_8H_8)Cl·2THF]_2和[Ln(C_8H_8)·2THF]等,还报

Eu~(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体的角重迭晶场参数计算

本文使用角重迭模型(AOM)在考虑其全部四个参数e_σ、e_π、e_δ和e_φ的基础上,对Eu~(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体的角量迭晶场参数进行了计算。结果表明,与σ、π反键有关的参数e_σ、e_x的数值相对较大,特别是e_σ值在这四个参数中为最大,而e_δ和e_α值则较小,在近似计算中可以忽略。这四种稀土硫氧化物的成键本领(或能力)按由大到小排列,其次序为Lu>Y>Gd>La。

LnBa_2C_3O_(7-δ)(Ln=Pr、Y)体系的XPS研究

该文研究了YBa_2Cu_3O_(7-δ)和PrBa_2Cu_3O_(7-δ)两体系的XPS谱图,结果表明从XPS图中难以判断三价铜的存在,与YBa_2Cu_3O_(7-δ)体系相比,PrBa_2Cu_3O_(7-δ)体系中Ba的结合能低,O_(18)的两个状态变得模糊不清。讨论了空穴浓度对高T_c超导电性的影响。

Eu~(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体的角重迭参数计算

本文使用角重迭模型(AOM),针对Eu~(3+):Ln_2O_2S(Ln=Lu,Y,Gd,La)晶体系列,在考虑硫和氧两种不同格位的情况下,对f电子的全部四个角重迭参数e_σ、e_π、e_δ和e_φ进行了计算,得到了一些基本规律,即中心离子与配位体之间的共价性大小次序为Lu～Y>Gd>La,并且Ln-O键的共价性要强于Ln-S键.

(η~5-C_9H_7)_3Ln·OC_4H_8(Ln=Nd、Gd、Er)的合成及晶体结构

合成了三茚基稀土配合物(η~5-C_9H_7)_3Ln·OC_4H_8(Ln=Nd、Gd、Er),经元素分析、红外光谱、水解产物核磁共振谱及质谱表征,并测得了(η~5-C_9H_7)_3Nd·OC_4H_8(1)及(η~5-C_9H_7)_3Gd·OC_4H_8(2)的晶体结构。(1)、(2)均属六方晶系,P6_3空间群,Z=2。(1)的晶体学参数为a=b=1.1843(3)nm,c=1.0304(4)nm,V=1.25165(87)nm~3,D_c=1.49g·cm~(-3),最后一致性因子R=0.049;(2)的晶体学参数a=b=1.1805(2)nm,c=1.0236(2)nm,V=1.23536(56)nm~3,D_c=1.54 g·cm~(-3),R=0.023。平均Nd-C=0.2812nm,Gd-C=0.2795nm;Nd-O=0.2557(21)nm,Gd—O=0.2459(13)nm。配合物中四氢呋喃的四个碳原子处于完全无序状态。

INVESTIGATION ON THE LUMINESCENCE PROPERTIES OF DY3+ AND EU3+ IN M3LN2(BO3)4 (M=CA, SR, BA, LN= LA, GD, Y)

In this paper, the luminescence properties of Dy3+ and Eu3+ in M3Ln2 (BO3)4 (M = Ca,Sr,Ba; Ln = La, Gd, Y) were systematically studied. The hypersensitive transitions of Dy3+ and Eu3+ were investigated in relation to the host compositions; the relationship between the energy of Eu3+ charge-transfer band and M2+ ion was discussed, and the concentration quenching of Dy3+ luminescence was reported.

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 AND CRYSTAL-STRUCTURES OF TRIINDENYLLANTHANIDE COMPLEXES (ETA-5-C9H7)3LN.OC4H8 (LN=ND,GD,ER)

The complexes named in the title (eta-5-C9H7)3Ln.OC4H8 (Ln = Nd, Gd, Er) were synthesized by the reaction of anhydrous lanthanide trichlorides with indenyl potassium and cyclooctadienyl potassium (1:2:1 molar ratio) in THF. The complexes were characterized by elemental analysis, infrared and H-1-NMR spectroscopy, and mass spectrometry. In addition, the crystal structures of (eta-5-C9H7)3Nd.OC4H8 (1) and (eta-5-C9H7)3Gd.OC4H8 (2) were determined by an X-ray diffraction study. Complexes 1 and 2 belong to hexagonal space group P6(3) with unit cell parameters a = b = 11.843(3), c = 10.304(4) angstrom, V = 1251.7(9) angstrom-3, D(c) = 1.49 g.cm-3, Z = 2 for 1, and a = b = 11.805(2), c = 10.236(2) angstrom, V = 1235.4(6) angstrom-3 D(c) = 1.54 g.cm-3, Z = 2 for 2. The structures were solved by Patterson and Fourier techniques and refined by least-squares to final discrepancy indices of R = 0.049, R(w) = 0.053 using 925 independent reflections with I greater-than-or-equal-to 3-sigma(I) for 1, and R = 0.023, R(w) = 0.025 using 1327 independent reflections with I greater-than-or-equal-to 3-sigma(I) for 2. Coordination numbers for Nd3+ and Gd3+ are 10; the average bond lengths Nd-O and Gd-O are 2.557(21) and 2.459(13) angstrom, respectively. The structural studies showed the complexes to have 3-fold symmetry, but the THF molecule has no such symmetry; consequently the arrangement of carbon atoms in the THF molecule are disordered.

稀土配合物导数吸收光谱研究Ⅳ.Ln~(3+)-Ferron-Triton X-100配合物导数光谱的研究及其应用

具有f-f超灵敏跃迁的稀土配合物导数吸收光谱可大幅度提高稀土元素的测定灵敏度,钕-高铁试剂(Ferron,7碘-8羟基喹啉-5-磺酸)即为此类配合物,但其测定灵敏度提高不多。研究发现,在Ln~(3+)(Pr~(3+)、Nd~(3+)、Er~(3+))-Ferron体系中加入表面活性剂可形成新的配合物,使其f-f超灵敏跃迁吸收谱线增强,峰形显著变化,其中钕和铒的吸收峰

稀土有机配合物[Li·3DME][(η~5-C'_P)_3LnCH_3](C'_P=C_5H_5,Ln=La,Nd;C'_P=CH_3C_5H_4,Ln=Nd)的合成及催化苯乙烯聚合的研究

环戊二烯基稀土烷基化合物是一类重要的具有催化活性的化合物.Ballard等首次报道了)类配合物是乙烯的均相聚合催化剂.Watson等报道可催化乙烯丙烯聚合,活化饱和C—H键.但是,由

SYNTHESIS OF A NEW TYPE OF CH3CN-COORDINATED LANTHANIDE COMPOUNDS LN(CH3CN)9(ALCL4)3CH3CN

Acetonitrile is a weakly donating ligand. The cationic compounds of CH_3CN-coordinated transition metal are versatile homogeneous catalysts for the polymerization and isomerization of olefins and cycloolefins. The cationic compound of lanthanide[Eu(CH_3·CN)_3(BF_4)_3]_n was prepared from the oxidation of Eu with NOBF_4 in CH_3CN by Thomas in 1986. It was found that [Eu(CH_3CN)_3(BF_4)_3]_n can catalyze the polymerization of styrene cyclohexadiene and other olefins. However, there is no information about...

Ln(CH_3CN)_9(AlCl_4)_3·CH_3CN配合物催化苯乙烯阳离子聚合的研究

报道了一类新型的离子型稀土乙腈配合物,Ln(CH_3CN)_9(AICl_4)_3·CH_3CN,催化苯乙烯阳离子聚合的结果。研究了聚合溶剂,单体浓度,反应温度以及配合物中稀土离子性质对催化活性和所得聚苯乙烯分子量的影响。发现稀土元素对聚合活性的影响顺序是La>Tb～Ho>Pr～Gd>Nd>Sm～Yb>Eu。聚合物的分子量明显地随着聚合温度的升高而降低。探讨了这类聚合反应的历程。