Structural Order–Disorder Transitions in Ln2Ti2O7 (Ln = Lu,Gd)

The phase generation in the Lu(Gd)–Ti–O systems is studied at 20–1000° using a co-precipitation method. During a thermal treatment of co-precipitation products after a sublimation dehydration, for a composition with the Lu : Ti cation ratio of 1 : 1, an Lu₂Ti₂O₇ phase with a fluorite structure forms at 650°. At 730–750°C the phase undergoes a fluorite pyrochlore transition. Above 750°C its structure is that of disordered pyrochlore, in which antistructural defects occur in Lu and Ti positions (up to 18%). Above 900°C the structure of pyrochlore becomes ordered, and the number of defects in Lu and Ti positions decreases, which affects the temperature dependence of permittivity of Lu₂Ti₂O₇. In Gd–Ti–O system, Gd₂Ti₂O₇ is crystallized, which has a pyrochlore structure only at 740–900°. Electroconductivity and permittivity of Lu₂Ti₂O₇ and Gd₂Ti₂O₇ are measured.     

Molecular Ln(III)−H−E(II) Linkages (Ln=Y,Lu; E=Ge,Sn, Pb)

Following the alkane-elimination route, the reaction between tetravalent aryl tintrihydride Ar*SnH₃ and trivalent rare-earth-metallocene alkyls [Cp*₂Ln(CH{SiMe₃}₂)] gave complexes [Cp*₂Ln(μ-H)₂SnAr*] implementing a low-valent tin hydride (Ln=Y, Lu; Ar*=2,6-Trip₂C₆H₃, Trip=2,4,6-triisopropylphenyl). The homologous complexes of germanium and lead, [Cp*₂Ln(μ-H)₂EAr*] (E = Ge, Pb), were accessed via addition of low-valent [(Ar*EH)₂] to the rare-earth-metal hydrides [(Cp*₂LnH)₂]. The lead compounds [Cp*₂Ln(μ-H)₂PbAr*] exhibit H/D exchange in reactions with deuterated solvents or dihydrogen.     

Syntheses of (C_5H_9C_5H_4)_2LnCl(THF)_n (Ln=Nd, Sm, Er, Yb) and crystal structure of [(C_5H_9C_5H_4)_2-LnCl(THF)_n]_2(Ln=Sm, n=1; Ln=Er, n=0)

Reactions of lanthanoid trichlorides with sodium cyclopentylcyclopentadienyl in THFafford bis(cyclopentylcyclopentadienyl) lanthanoid chloride complexes (C_5H_9C_5H_4)_2LnCl(THF)_n (Ln=Nd, Sm, n=1; Ln= Er, Yb, n= 0). The compound [CP'_2SmCl(THF)]_2 (2) (Cp' =cyclopentylcy-clopentadienyl) crystallizes from mixed solvent of hexane and THF in monoclinic space group P_2_1/cwith a = 11.583 (3), b = 23.019(6), c = 8.227 (2), β= 90.26 (2)°, V= 2194 (1)~3, D_c= 1.59 g/cm~3.μ= 28.6 cm~(-1), F(000) = 1060, Z= 2 (dimers). Its crystal molecule is a dimer with a crystallographicsymmetry center. The central metal atom Sm is coordinated to two Cp' rings, two bridging chlorineatoms and one THF forming a distorted trigonal bipyramid. The crystal of [Cp'_2ErCl]_2 (3) belongs tothe triclinic space group P with a = 11.264 (2), b= 13.296(5), c = 14.296(6), a = 96.99 (3), β=112.47(2), γ= 102.78(2)°, V= 1865(1)~3, D_c= 1.67 g /cm~3, μ= 48.0 cm~(-1), F(000) = 924, Z = 2 (dimers).The molecule is a dimer consisting of two Cp'_2 ErCl species bridged by two Cl atoms. The centralmetal atom Er is coordinated to two Cp' rings and two bridging chlorine atoms forming a pseudo-tetrahedron. All these complexes are soluble in THF, DME, Et_2O, toluene and hexane.     

Synthesis and structural characterization of lanthanide oxalate–oxydiacetate mixed-ligand coordination polymers {[Ln(oda)(H2O) x ]2(ox)} n ( x = 3 for Ln = La,Ce, Pr,Gd, Tb and x = 2 for Ln = Er)

Reactions of oxydiacetic acid (H₂oda) with lanthanide oxide, nitrate, chloride, and carbonate gave six lanthanide oxalate–oxydiacetate mixed-ligand coordination polymers {[Ln(oda)(H₂O) _x ]₂(ox)} _n [x = 3 for Ln = La, Ce, Pr, Gd, Tb, (1–5), and x = 2 for Ln = Er (6)]. Oxydiacetic acid is decomposed into oxalic acid in this reaction. In the crystal structures of 1–6, oxydiacetate and the lanthanides build a chain, and the oxalate groups bridge two chains to form 1-D double-chain ladder-shaped structures, connected by intermolecular hydrogen bonds to form a 2-D network structure. These compounds contain approximately 3.0 × 6.4 Ų channels along the c-axis. The infrared spectra and thermal behaviors of 1–6 are also investigated.     

三元体系Ln(ClO~4)~3-ACAP-H~2O(Ln=La,Sm,Yb)的相平衡研究(30℃)

测定了三元体系Ln(ClO~4)~3-ACAP-H~2O(Ln=La,Sm,Yb, ACAP=4-乙酰安替比林)在30℃时的溶解度及饱和溶液的折光率,绘制了相应的溶度图和饱和溶液的折光率-组成图.体系的溶度曲线和折光率曲线均由三支组成,分别与ACAP,Ln(ACAP)~3(ClO~4)~3·nH~2O(Ln=La,n=4,Sm,2,Yb,2)和Ln(ClO~4)~3·nH~2O(Ln=La,n=8,Sm,9,Yb,8)相对应.从溶度图上发现了三个未见文献报道的三元化合物, 它们均为固液异组成溶解的化合物.通过化学分析,元素分析,TG-DTG,IR,UV和X射线粉末衍射进行了表征.初步探讨了影响安替比林4位酰代衍生物β-二酮配体配位能力的因素     

水热法制备近红外发光NaLa(WO4)2∶Ln(Ln=Er, Nd)球形粒子的研究

利用水热法制备了NaLa（WO4）2∶Ln（Ln=Er,Nd）球形粉末,分别用XRD,TEM和发光光谱等对粉末的物相、形貌、发光性质进行研究。XRD和SEM结果表明：制得的NaLa（WO4）2∶Ln（Ln=Er,Nd）粉末为白钨矿晶型,分散性良好,粒度均匀,呈规则的球形,粒径为1μm左右。发光光谱的测试表明：样品的最佳掺杂浓度为1.0%;随着煅烧温度的增加,样品发光强度逐渐增大;700℃下煅烧时最佳煅烧时间是4 h。     

Synthesis and photoluminescence of complexes Tm(L)(iso-Bu2PS2)2(NO3) (L = Phen, 2,2′-Bipy). Crystal structures of compounds [Ln(2,2′-Bipy)(iso-Bu2PS2)2(NO3)] · C6H6 (Ln = Tm, Tb)

Heteroligand complexes Tm(L)(iso-Bu₂PS₂)₂(NO₃) (L = 2,2′-Bipy (II), Phen (III)) are synthesized. According to the X-ray phase analysis data, complex III is isostructural to mononuclear compound [Dy(Phen)(iso-Bu₂PS₂)₂(NO₃)] including, according to the X-ray diffraction data, a coordination polyhedron DyN₂O₂S₄ (distorted dodecahedron). Single crystals of compounds [Ln(2,2′-Bipy)(iso-Bu₂PS₂)₂(NO₃)] · C₆H₆ (Ln = Tm (IV), Tb (V)) are obtained. An X-ray diffraction analysis shows that the crystal structures of these isostructural compounds are formed by molecules of mononuclear complexes [Ln(2,2′-Bipy)(iso-Bu₂PS₂)₂(NO₃) and uncoordinated C₆H₆ molecules. In complexes IV and V, the ligands [Ln(2,2′-Bipy)(iso-Bu₂PS ₂ ^? , and NO ₃ ^? are bidentate-cyclic. The coordination polyhedron LnN₂O₂S₄ is a distorted dodecahedron. Complexes II and III possess photoluminescence in the visible spectral range (λ_max = 478 and 477 nm, respectively).     

三元体系Ln(ClO4)3-4-ClCH2COAp-H2O(30℃)的相平衡研究(Ln=La,Sm,Er)

我们测定了三元体系Ln(ClO4)3-4-ClCh2COAp-H2O(Ln=La,Er)在30℃时的溶度及饱和溶液的折光指数,绘制相应的溶度图和饱和溶液的折光指数曲线图。体系的溶度曲线和折光指数曲线均由四支组成,分别与4-ClCh2COAp、Ln(4-ClCh2COAp)3·nH2O(Ln=La,n=7;Sm,8;Er,4)、Ln(4-ClCH2COAp)2(ClO4)3·nH2O(Ln-La,n=7;Sr,6;Er,4)和Ln(ClO4)3·nH2O(Ln=La,n=8;Sm,9;Er,6)相对应,两类配合物均为固液异组成化合物。     

The magnetochemistry of novel cyano-bridged complexes Ln(DMF)4(H2O)2Mn(CN)6 · H2O (Ln = Tb,Dy, Er)

Using K₃Mn(CN)₆, DMF and Ln(NO₃)₃ · 6H₂O (Ln = Tb, Dy or Er), novel cyano-bridged complexes Ln(DMF)₄(H₂O)₂Mn(CN)₆ · H₂O (TbMn, DyMn and ErMn, respectively) were prepared and their magnetochemical properties were studied in detail. A weak antiferromagnetic interaction was found to exist between the rare earth ions and the manganese ion. Er(DMF)₄(H₂O)₂Mn(CN)₆ · H₂O, in particular, exhibits long-range magnetic ordering, a higher critical temperature (T _c = 17.5 K) and a stronger coercive force (H _c = 980 Oe).     

三元体系Ln(ClO4)3-4-ClCH2COAp-H2O(30℃)的相平衡研究(Ln=La,Sm,Er)

我们测定了三元体系 Ln(ClO_4)_3—4-ClCH_2COA_p—H_2O(Ln=La,Sm,Er)存30℃时的溶度及饱和溶液的折光指数,绘制了相应的溶度图和饱和溶液的折光指数曲线图.体系的溶度曲线和折光指数曲线均由四支组成,分别与4-ClCH_2COA_p、Ln(4-ClCH_2COAp)_3(ClO_4)_3·nH_2O(Ln=La,n=7;Sm,8;Er,4)、Ln(4-ClCH_2COAp)_2(ClO_4)_3·nH_2O(Ln=La,n=7;Sm,6;Er,4)和 Ln(ClO_4)_3·nH_2O(Ln=La,n=8;Sm,9;Er,6)相对应,两类配合物均为固液异组成化合物.     

系列Ln(Ⅲ)配位聚合物(Ln=Eu,Sm,Tb,Pr,Gd)的合成及其荧光分析

采用水热法合成了4个具有1D结构的Ln(Ⅲ)配位聚合物,[Eu₂(C₉H₇O₂)₆(C₉H₇O₂H)(C₂H₅OH)]n(1)、[Sm(C₉H₇O₂)₃]n(2)、[Tb(C₉H₇O₂)₃]n(3)和[Gd(C₉H₇O₂)₃]n(4)(C₉H₈O₂=肉桂酸)。 通过X射线单晶衍射确定了它们的结构。 这4个Ln(Ⅲ)配合物中,Ln(Ⅲ)的配位数均为9,桥配体均为肉桂酸根,但其配位方式有差异。 对配合物进行了IR、UV-Vis-NIR和荧光光谱等表征。 分析了各配合物的荧光发射,结果表明,在可见区,配合物1发射较明显的红光,配合物2、3发射绿光,配合物4发射蓝光,但很弱。 讨论了具有刚柔相混杂性质的肉桂酸配体对配位聚合物的构筑及稀土离子发光的影响。     

Synthesis and thermal decomposition of lanthanide hexacyanochromate(iii) complexes,Ln[Cr(CN)6]·nH2O (Ln=La-Lu; n=3, 4)

New solid complex of nitrilotriacetic acid and bismuth trichloride was synthesized by a solid phase reaction of nitrilotriacetic acid and bismuth trichloride at room temperature. The composition of the sample is BiCl₃[N(CH₂COOH)₃]_2.5. The crystal structure of the complex belongs to triclinic system with the lattice parameters: α=0.7849 nm, β=0.9821 nm, χ=2.0021 nm, α=96.50°, β=98.76° and γ=90.49°. The far-infrared spectra show the bonding between the Bi ion and N atom of nitrilotriacetic acid. The thermal analysis also demonstrates the complex formation between the bismuth ion and nitrilotriacetic acid. The gaseous pyrolysis product and the final residue in the thermal decomposition process are determined to check the thermal decomposition reaction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and Characterization of Ethylthioethylcyclopenta-dienyl Organolanthanide Complexes:Cp_2~(Th)LnCl(Ln=Gd,Dy),Cp_2LnCp~(Th)(Ln=Yb,Sm,Dy,Y) and Cp~(Th)ErCl_2·2THF

Introduction Functional substituted cyclopentadienyl organolan-thanide complexes continue to attract considerable at-tention because these donor-functionalized side chains can increase the stability of highly reactive organolan-thanide complexes by forming the additional in-tramolecular chelating coordination with the central metal, and for early lanthanide complexes, the enhanced stability offers the opportunity to explore the reactivity of the remaining ligands.1-4 In addition, the in-tramol…     

LnCu_2O_4(Ln=Gd,Nd)电子结构的XPS研究

用 XPS测定了 LnCu2O4(Ln=Gd, Nd)的内层和价层电子能谱,观察到 LnCu2O4中稀土金属的 3d电子结合能比相应的稀土金属简单氧化物的 3d结合能低 0.8～ 0.9 eV,而 Cu的 2p电子结合能比 CuO的高 0.4～ 0.5 eV,因此推断在 LnCu2O4的 Ln－ O－ Cu链中存在 Cu→ O→ Ln电荷转移 .XPS分析还表明 LnCu2O4的 Cu原子上有较低的电荷密度,但不存在混合价态 .此外,通过比较价电子能谱,发现 NdCu2O4的 Ln 4f Cu 3d O 2p价带中心比 GdCu2O4的价带中心向 Fermi能级移近了 3.4 eV,而且 NdCu2O4的价带谱更窄 .     

Hydrothermal Synthesis,Crystal Structures,and Fluorescence Properties of Ni(II)–Ln(III) Complexes (Ln = Sm,Pr, Eu)

Three novel 3d–4f heterometal complexes [Ln(NiL)₃(Btca)(NO₃)] · xH₂O (Ln = Sm(III) (I), Pr(III) (II), Eu(III) (III) (H₂L = 2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-dien, H₂Btca = benzotriazole-5-carboxylic acid) were solvothermally synthesized and characterized by singlecrystal X-ray diffraction (CIF files CCDC nos. 1555557 (I), 1555555 (II), 1555556 (III)). They crystallized in the monoclinic space group P2₁/n for I (x = 1.5) and C2/c for (II) and (III) (x = 1), respectively. In these complexes, the central Ln(III) and external nickel ions are bridged by macrocyclic oxamide groups. The metal center of Ln(III) resides in a distorted bicapped square antiprism surrounding with six oxygen atoms of three oxamide groups, two oxygen atoms of Btca^2– ion and two oxygen atoms of NO₃^-. Furthermore, there are C–H···O and/or C–H···N hydrogen bond interactions among nitrate, benzotriazole-5-carboxylate, macrocyclic oxamide and water to form three-dimensional superamolecular architecture. The fluorescence properties of the compounds I and II are also discussed.     

CRYSTAL STRUCTURES OF Ln(o-ClC_6H_4CO_2)_3(H_2O)[Ln = Tb(Ⅲ) , Nd(Ⅲ)]

<正> Ln(o-ClC6H4CO2)3 (H2O) (Ln = Tb,Nb) ,Mr = 643. 62[628. 89]**, monoclinic,space group P21/n,a=12. 360(2)[12. 373(5)],b=6. 908(0)[7. 021(2)], c = 25. 936(6) [26. 086(9)] A ,β= 101. 30(2) [101. 71 (3)]°,Z= 4,V = 2171. 5(6) [2219(1)] A3,Dc=1. 97[1. 88]g·cm-3,μ= 37. 5[27. 5]em-1 (MoKa) ,F(000) = 1248[1228]. The two compounds are isomorphous,they show infinite chain structure.     

ELECTRONIC STRUCTURE AND CHEMICAL BONDING OF BIS(TRIMETHYLSILYL)AMIDE DERIVATIVES OF LANTHANIDES(Ln(N(SiMe_3)_2)_3, Ln=Nd, Eu, Yb)

The electronic structure and chemical bonding of Ln(N(SiMe_3)_2)_3 have been studied by INDO calcula-tions. The results have shown that the Ln-N bonds are considerably covalent in character and that thecovalency decreases with increasing atomic numbers. A new explanation of the pyramidal structure of thecompounds has been proposed based on 5d orbital participation in bonding. With the calculation of asimplified model of Eu(N(SiMe_3)_2)_3. OPPh_3, the roles of electronic and steric effects in bonding have beencompared.     

镧系元素双三甲基硅胺基络合物(Ln(N(SiMe_3)_2)_3,Ln=Nd,Eu,Yb)的电子结构和化学键

本文采用自旋不限制的INDO方法,首次研究了Ln(N(SiMe_3)_2)_3络合物(Ln=Nd,Eu,Yb)的电子结构和化学键。结果表明,金属和配位体之间的化学键具有很强的共价性,共价性随原子序数增加而减弱。根据5d轨道成键对络合物奇特的三角锥结构提出了新的解释。计算了双三甲基硅胺基铕的OPPh_3加合物的电子结构,并讨论了电子结构和位阻效应在配位化学中的作用。     

Ln2Cl 7 − ions (Ln = La and Lu): Structures and thermodynamic stability

The equilibrium geometrical parameters and frequencies of the normal vibrations of Ln₂Cl ₇ ^? ions (Ln = La and Lu) and the enthalpies of the dissociation reactions Ln₂Cl ₇ ^? → Ln₂Cl₆ + Cl^? and Ln₂Cl ₇ ^? → LnCl₃ + LnCl ₄ ^? were calculated at the MP2 and MP4 levels (with regard to single, double, triple, and quadruple perturbations). The basis set superposition errors were eliminated by using the counterpoise approach. The potential energy surface of the Ln₂Cl ₇ ^? ions was found to reach a minimum for a configuration with three bridging and four terminal Cl atoms (symmetry C ₂). The terminal fragments LnCl₂ show almost free inherent rotation. The lanthanide compression of the interatomic Ln-Cl distances differed for the bridging and terminal Ln-Cl bonds. The calculated enthalpies of dissociation of the Ln₂Cl ₇ ^? ions were compared with data from high-temperature mass spectrometry.