New luminescent solids in the Ln-W(Mo)-Te-O-(Cl) systems

Solid-state reactions of lanthanide(III) oxide (and/or lanthanide(III) oxychloride), MoO3 (or WO3), and TeO2 at high temperature lead to eight new luminescent compounds with four different types of structures, namely, Ln2(MoO4)(Te4O10) (Ln = Pr, Nd), La2(WO4)(Te3O7)2, Nd2W2Te2O13, and Ln5(MO4)(Te5O13)(TeO3)2Cl3 (Ln = Pr, Nd; M = Mo, W). The structures of Ln2(MoO4)(Te4O10) (Ln = Pr, Nd) feature a 3D network in which the MoO4 tetrahedra serve as bridges between two lanthanide(III) tellurite layers. La2(WO4)(Te3O7)2 features a triple-layer structure built of a [La2WO4]4+ layer sandwiched between two Te3O72- anionic layers. The structure of Nd2W2Te2O13 is a 3D network in which the W2O108- dimers were inserted in the large tunnels of the neodymium(III) tellurites. The structures of Ln5(MO4)(Te5O13)(TeO3)2Cl3 (Ln = Pr, Nd; M = Mo, W) feature a 3D network structure built of lanthanide(III) ions interconnected by bridging TeO32-, Te5O136-, and Cl- anions with the MO4 (M = Mo, W) tetrahedra capping on both sides of the Ln4 (Ln = Pr, Nd) clusters and the isolated Cl- anions occupying the large apertures of the structure. Luminescent studies indicate that Pr2(MoO4)(Te4O10) and Pr5(MO4)(Te5O13)(TeO3)2Cl3 (M = Mo, W) are able to emit blue, green, and red light, whereas Nd2(MoO4)(Te4O10), Nd2W2Te2O13, and Nd5(MO4)(Te5O13)(TeO3)2Cl3 (M = Mo, W) exhibit strong emission bands in the near-IR region.     

Syntheses, structures, magnetism, and optical properties of lutetium-based interlanthanide selenides

Ln3LuSe6 (Ln = La, Ce), beta-LnLuSe3 (Ln = Pr, Nd), and LnxLu4-xSe6 (Ln = Sm, Gd; x = 1.82, 1.87) have been synthesized using a Sb2Se3 flux at 1000 degrees C. Ln3LuSe6 (Ln = La, Ce) adopts the U3ScS6-type three-dimensional structure, which is constructed from two-dimensional 2(infinity)[Ln3Se6](3-) slabs with the gaps between these slabs being filled by octahedrally coordinated Lu(3+) ions. The series of beta-LnLuSe3 (Ln = Pr, Nd) are isotypic with UFeS3. Their structures include layers formed from LuSe6 octahedra that are separated by eight-coordinate Ln(3+) (Ln = Pr, Nd) ions in bicapped trigonal prismatic environments. Sm1.82Lu2.18Se6 and Gd1.87Lu2.13Se6 crystallize in the disordered F-Ln2S3 type structure with the eight-coordinate bicapped trigonal prismatic Ln(1) ions residing in the one-dimensional channels formed by three different double chains via edge- and corner-sharing. These double chains are constructed from Ln(2)Se7 monocapped trigonal prisms, Ln(3)Se6 octahedra, and Ln(4)S6 octahedra, respectively. The magnetic susceptibilities of beta-PrLuSe3 and beta-NdLuSe3 follow the Curie-Weiss law. Sm1.82Lu2.18Se6 shows van Vleck paramagnetism. Magnetic susceptibility measurements show that Gd1.87Lu2.13Se6 undergoes an antiferromagnetic transition around 4 K. Ce3LuSe6 exhibits soft ferromagnetism below 5 K. The optical band gaps for La3LuSe6, Ce3LuSe6, beta-PrLuSe3, beta-NdLuSe3, Sm1.82Lu2.18Se6, and Gd1.87Lu2.13Se6 are 1.26, 1.10, 1.56, 1.61, 1.51, and 1.56 eV, respectively.     

Tris(dithiolene) complexes of neodymium and cerium: mononuclear species, chains, and honeycomb networks

Reactions of Ln(BH4)3(THF)3 (Ln = Nd, Ce) and M2dddt (M = Na, K; dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) in THF or pyridine gave, after addition of 18c6 (18-crown-6), several crystalline compounds which all contain the tris(dithiolene) Ln(dddt)3 unit. Crystals of [Na(18c6)(py)2]2[Na(18c6)(py)][Nd(dddt)3(py)].3py (1.3py) are built up from discrete mononuclear cationic and anionic species whereas crystals of {[Na(18c6)(py)2](0.5)[Na(18c6)(py)(1.5)][Na(1.5)Nd(dddt)3]}(infinity) (2) are composed of discrete [Na(18c6)(py)x]+ cations and polymeric anionic two-dimensional layers in which the Nd(dddt)3 units are linked to three neighbors by sodium atoms to form a honeycomb network. Analysis of the temperature dependence of the molar magnetic susceptibility of 2 shows that chiMT decreases from 1.63 cm3 K mol(-1) at 300 K down to 0.6 cm3 K mol(-1) at 5 K, due to the crystal-field splitting of the (4)I(9/2) free-ion state. Complexes {[Na3(18c6)(1.5)Nd(dddt)3(THF)].3THF}(infinity) (3.3THF) and {[K3(18c6)(1.5)Nd(dddt)3(py)].3py}(infinity) (4.3py) exhibit neutral polymeric layers with the Nd(dddt)3 units linked by M2(18c6) fragments. In the cerium compound {[Na2(18c6)Na(py)2Ce(dddt)3(py)].3py}(infinity) (5.3py), each Ce(dddt)3 unit is linked to two neighbors only by Na2(18c6) moieties, giving infinite zigzag chains.     

Syntheses, structure, some band gaps, and electronic structures of CsLnZnTe3 (Ln=La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Y)

Eleven new quaternary rare-earth tellurides, CsLnZnTe3 (Ln=La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Y), were prepared from solid-state reactions at 1123 K. These isostructural materials crystallize in the layered KZrCuS3 structure type in the orthorhombic space group Cmcm. The structure is composed of LnTe6 octahedra and ZnTe4 tetrahedra that share edges to form [LnZnTe3] layers. These layers stack perpendicular to [010] and are separated by layers of face- and edge-sharing CsTe8 bicapped trigonal prisms. There are no Te-Te bonds in the structure of these CsLnZnTe3 compounds so the formal oxidation states of Cs/Ln/Zn/Te are 1+/3+/2+/2-. Optical band gaps of 2.13 eV for CsGdZnTe3 and 2.12 eV for CsTbZnTe3 were deduced from single-crystal optical absorption measurements. A first-principles calculation of the density of states and the frequency-dependent optical properties was performed on CsGdZnTe3. The calculated band gap of 2.1 eV is in good agreement with the experimental value. A quadratic fit for the lanthanide contraction of the Ln-Te distance is superior to a linear one if the closed-shell atom is included.     

Synthese und Aufbau von (4-Picolinium)[LnCl4(H2O)3] (Ln = La,Ce, Pr,Nd)

Preparation and Crystal Structure of (4-Picolinium)[LnCl₄(H₂O)₃] (Ln = La, Ce, Pr, Nd) The complex water containing chlorides (4-Picolinium)[LnCl₄(H₂O)₃] (Ln = La, Ce, Pr, Nd) were prepared for the first time, and the crystal structures of (4-Picolinium)[LnCl₄(H₂O)₃] (Ln = La, Pr) were determined on single crystals by X-ray methods. The isotypic compounds crystallize with triclinic symmetry, space group P1 , Z = 2. Surprisingly there exist the dimeric complex anions [Ln₂Cl₈(H₂O)₆]^2? (Ln = La, Pr).     

Rare-earth tricyanomelaminates [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)H(2)O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy): structural investigation, solid-state NMR spectroscopy, and photoluminescence

The rare-earth tricyanomelaminates, [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)xH(2)O (LnTCM; Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy), have been synthesized through ion-exchange reactions. They have been characterized by powder as well as single-crystal X-ray diffraction analysis, vibrational spectroscopy, and solid-state (1)H, (13)C, and (15)N MAS NMR spectroscopy. The X-ray powder pattern common to all nine rare-earth tricyanomelaminates LnTCM (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) indicates that they are isostructural. The single-crystal X-ray diffraction pattern of LnTCM is indicative of non-merohedral twinning. The crystals are triclinic and separation of the twin domains as well as refinement of the structure were successfully carried out in the space group P1 for LaTCM (LaTCM; P1, Z=2, a=7.1014(14), b=13.194(3), c=13.803(3) A, alpha=90.11(3), beta=77.85(3), gamma=87.23(3) degrees , V=1262.8(4) A(3)). In the crystal structure, each Ln(3+) is surrounded by two nitrogen atoms from two crystallographically independent tricyanomelaminate moieties and seven oxygen atoms from crystal water molecules. The positions of all of the hydrogen atoms of the ammonium ions and water molecules could not be located from difference Fourier syntheses. The presence of [NH(4)](+) ions as well as two NH groups belonging to two crystallographically independent monoprotonated tricyanomelaminate moieties has only been confirmed by subjecting LaTCM to solid-state (1)H, (13)C, and (15)N{(1)H} cross-polarization (CP) MAS NMR and advanced CP experiments such as cross-polarization combined with polarization inversion (CPPI). The (1)H 2D double-quantum single-quantum homonuclear correlation (DQ SQ) spectrum and the (15)N{(1)H} 2D CP heteronuclear-correlation (HETCOR) spectrum have revealed the hydrogen-bonded (N--HN) dimer of monoprotonated tricyanomelaminate moieties as well as H-bonding through [NH(4)](+) ions and H(2)O molecules. The structures of the other eight rare-earth tricyanomelaminates (LnTCM; Ln=Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) have been refined from X-ray powder diffraction data by the Rietveld method. Photoluminescence studies of [NH(4)]Eu[HC(6)N(9)](2)[H(2)O](7)xH(2)O have revealed orange-red (lambda(max)=615 nm) emission due to the (5)D(0)-(7)F(2) transition, whereas [NH(4)]Tb[HC(6)N(9)](2)[H(2)O](7)xH(2)O has been found to show green emission with a maximum at 545 nm arising from the (5)D(4)-(7)F(5) transition. DTA/TG studies of [NH(4)]Ln[HC(6)N(9)](2)[H(2)O](7)xH(2)O have indicated several phase transitions associated with dehydration of the compounds above 150 degrees C and decomposition above 200 degrees C.     

Ln(14)Na(3)Ru(6)O(36) (ln = pr, nd): two new complex lanthanide-containing oxides of ruthenium

The lanthanide-containing ruthenium oxides Ln14Na3Ru6O36 (Ln = Pr, Nd) were prepared as single crystals from molten sodium hydroxide. The two compounds crystallize in the rhombohedral space group Rc with cell constants of a = 9.7380(2) and 9.6781(2) Angstrom and c = 55.5716(18) and 55.4156(18) Angstrom for Ln14Na3Ru6O36 (Ln = Pr, Nd), respectively. The structure of the two compounds is composed of two types of slabs that alternate in an AB fashion. Each slab consists of three layers and are arranged to yield a unit cell with a 12-layer structure. Both compounds exhibit magnetic behavior consistent with canted antiferromagnetism.     

Orthonitridoborate ions [BN3]6- in oxonitridosilicate cages: synthesis, crystal structure, and magnetic properties of Ba4Pr7[Si12N23O][BN3], Ba4Nd7[Si12N23O][BN3], and Ba4Sm7[Si12N23O][BN3

The isotypic title compounds Ba4Pr7[Si12N23O][BN3], Ba4Nd7[Si12N23O][BN3], and Ba4Sm7[Si12N23O][BN3] were prepared by reaction of Pr, Nd, or Sm, with barium, BaCO3, Si(NH)2, and poly(boron amide imide) in nitrogen atmosphere in tungsten crucibles using a radiofrequency furnace at temperatures up to 1650 C. They were obtained as main products (approximately 70%) embedded in a very hard glass matrix in the form of intense dark green (Pr), orange-brown (Sm), or dark red (Nd) large single crystals, respectively. The stoichiometric composition of Ba4Sm7[Si12N23O][BN3] was verified by a quantitative elemental analysis. According to the single-crystal X-ray structure determinations (Ba4Ln7[Si12N23][BN3], Z= , P6 with Ln = Pr: a = 1225.7(1), c = 544.83(9) pm, R1 = 0.013, wR2 = 0.030; Ln = Nd: a = 1222.6(1), c = 544.6(1) pm, R1 = 0.017, wR2 = .039; Ln = Sm: a = 1215.97(5), c = 542.80(5) pm, R1 = 0.047, wR2 = 0.099) all three compounds are built up by a framework structure [Si12N23O]23- of corner-sharing SiX4 tetrahedrons (X = O, N). The oxygen atoms are randomly distributed over the X positions. The trigonal-planar orthonitridoborate ions [BN3]6- and also the Ln(3)3+ are situated in hexagonal cages of the framework (bond lengths Si-(N/O) 169-179 pm for Ln=Pr). The remaining Ba2+ and Ln3- ions are positioned in channels of the large-pored network. The trigonal-planar [BN3]6- ions have a B-N distance of 147.1(6) pm (for Ln = Pr). Temperature-dependent susceptibility measurements for Ba4Nd7[Si12N23O][BN3] revealed Curie-Weiss behavior above 60 K with an experimental magnetic moment of muexp = 3.36(5) microB/Nd. The deviation from Curie-Weiss behavior below 60 K may be attributed to crystal field splitting of the J = 9/2 ground state of the Nd3+ ions. No magnetic ordering is evident down to 4.2 K.     

两类稀土钒酸盐的合成与结构

通过（１）ＬｎＯＣｌ／Ｖ＿２Ｏ＿５，（２）ＬｎＣｌ３／Ｖ及（３）ＬｎＯＣｌ／ＬｎＣｌ／Ｖ＿２Ｏ＿５／Ｖ的高温固态化学反应，得到两种稀土钒酸盐：Ｌｎ＿６Ｖ＿３Ｃｌ＿（１０）Ｏ＿（１２）（Ｌｎ＝Ｌａ）及Ｌｎ＿４Ｖ＿５Ｓｉ＿４Ｏ＿（２２）（Ｌｎ＝Ｌａ～Ｎｄ）。Ｌａ＿６Ｖ＿３Ｏ＿（１０）Ｏ＿（１２）晶体呈浅色透明片状，其结构可认为是由［Ｌａ＿３（ＶＯ＿４）＿３Ｃｌ］单元插入到ＬａＣｌ３结构单元中而形成的，在结构中沿ｃ轴方向存在一系列截面积为１９．１的空洞。Ｌｎ＿４Ｖ＿５Ｓｉ＿４Ｏ＿（２２）（Ｌｎ＝Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ）晶体呈，黑色针状，其结构可认为是由交替的稀土钒硅酸盐薄层及钒氧金红石层沿ｃ轴堆叠而表现为准二维Ｃｈｅｖｋｉｎｉｔｅ型结构。     

Structural and photophysical properties of coordination networks combining [Ru(Bpym)(CN)4]2- or [[Ru(CN)4]2(mu-bpym)]4- anions (bpym = 2,2'-bipyrimidine) with lanthanide(III) cations: sensitized near-infrared luminescence from Yb(III), Nd(III), and Er(III) following Ru-to-lanthanide energy transfer

Reaction of the cyanoruthenate anions [Ru(bpym)(CN)4]2- and [[Ru(CN)4]2(mu-bpym)]4- (bpym = 2,2'-bipyrimidine) with lanthanide(III) salts resulted in the crystallization of coordination networks based on Ru-CN-Ln bridges. Four types of structure were obtained: [Ru(bpym)(CN)4][Ln(NO3)(H2O)5] (Ru-Ln; Ln = Sm, Nd, and Gd) are one-dimensional helical chains; [Ru(bpym)(CN)4]2[Ln(NO3)(H2O)2][Ln(NO3)(0.5)(H2O)(5.5)](NO3)(0.5).5.5H2O (Ru-Ln; Ln = Er and Yb) are two-dimensional sheets containing cross-linked chains based on Ru2Ln2(mu-CN)4 diamond units, which are linked into one-dimensional chains via shared Ru atoms; [[Ru(CN)4]2(mu-bpym)][Ln(NO3)(H2O)5]2.3H2O (Ru2-Ln; Ln = Nd and Sm) are one-dimensional ladders with parallel Ln-NC-Ru-CN-Ln-NC strands connected by the bipyrimidine "cross pieces" acting as rungs on the ladder; and [[Ru(CN)4]2(mu-bpym)][Ln(H2O)6](0.5)[Ln(H2O)4](NO3)(0.5).nH2O (Ru2-Ln; Ln = Eu, Gd, and Yb; n = 8.5, 8.5, and 8, respectively) are three-dimensional networks in which two-dimensional sheets of Ru2Ln2(mu-CN)4 diamonds are connected via cyanide bridges to Ln(III) ions between the layers. Whereas Ru-Gd shows weak triplet metal-to-ligand charge-transfer (3MLCT) luminescence in the solid state from the Ru-bipyrimidine chromophore, in Ru-Nd, Ru-Er, and Ru-Yb, the Ru-based emission is quenched, and all of these show, instead, sensitized lanthanide-based near-IR luminescence following a Ru --> Ln energy transfer. Similarly, Ru2-Nd and Ru2-Yb show lanthanide-based near-IR emission following excitation of the Ru-bipyrimidine chromophore. Time-resolved luminescence measurements suggest that the Ru --> Ln energy-transfer rate is faster (when Ln = Yb and Er) than in related complexes based on the [Ru(bipy)(CN)4]2- chromophore, because the lower energy of the Ru-bpym 3MLCT provides better spectroscopic overlap with the low-energy f-f states of Yb(III) and Er(III). In every case, the lanthanide-based luminescence is relatively short-lived as a result of the CN oscillations in the lattice.     

Layered rare-earth gallium antimonides REGaSb(2) (RE = La--Nd, Sm).

The ternary rare-earth gallium antimonides, REGaSb(2) (RE = La--Nd, Sm), have been synthesized through reaction of the elements. The structures of SmGaSb(2) (orthorhombic, space group D(5)(2)-C222(1), Z = 4, a = 4.3087(5) A, b = 22.093(4) A, c = 4.3319(4) A) and NdGaSb(2) (tetragonal, space group D(19)(4h)-I4(1)/amd, Z = 8, a = 4.3486(3) A, c = 44.579(8) A) have been determined by single-crystal X-ray diffraction. The SmGaSb(2)-type structure is adopted for RE = La and Sm, whereas the NdGaSb(2)-type structure is adopted for RE = Ce--Nd. The layered SmGaSb(2) and NdGaSb(2) structures are stacking variants of each other. In both structures, two-dimensional layers of composition (2)(infinity)[GaSb] are separated from square nets of Sb atoms [Sb] by RE atoms. Alternatively, the structures may be considered as resulting from the insertion of zigzag Ga chains between (2)(infinity)[RE Sb(2)] slabs. In SmGaSb(2), all of the Ga chains are parallel and the (2)(infinity)[SmSb(2)] layers are stacked in a ZrSi(2)-type arrangement. In NdGaSb(2), the Ga chains alternate in direction, resulting in a doubling of the long axis relative to SmGaSb(2), and the (2)(infinity)[NdSb(2)] layers are stacked in a Zr(3)Al(4)Si(5)-type arrangement. Extended Hückel band structure calculations are used to explain the bonding in the [GaSb(2)](3-) substructure.     

Reactions of lanthanoid metals with 3,5-diphenylpyrazole at elevated temperatures: synthesis and structures of both homoleptic, [Ln3(Ph2pz)9] (Ln = La, Nd), [Ln2(Ph2pz)6] (Ln = Er, Lu), and heteroleptic, [Ln(Ph2pz)3(Ph2pzH)2] (Ln = La, Nd, Gd, Tb, Er or Yb), pyrazolate complexes

The direct reaction of lanthanoid metals with 3,5-diphenylpyrazole (Ph2pzH) at 300 degrees C under vacuum in the presence of mercury gives the structurally characterized [Ln3(Ph2pz)9] (Ln = La or Nd), [Ln2(Ph2pz)6] (Ln = Er or Lu). Similar reactions provided heteroleptic [Ln(Ph2pz)3(Ph2pzH)2] (Ln = La, Nd, Gd, Tb, Er and Y). The last was obtained only from impure Ph2pzH, but was subsequently prepared by treatment of [Yb(Ph2pz)3(thf)2] with Ph2pzH. Reactions of Yb with Ph2pzH at 200 degrees C gave a poorly soluble divalent species which was converted by 1,2-dimethoxyethane into [Yb(Ph2pz)2(dme)2]. Single crystal X-ray structures established a bowed trinuclear pyrazolate-bridged structure for [Ln3(Ph2pz)9] (Ln = La or Nd), Ln...Ln...Ln being 135.94(1) degrees (La) and 137.41(1) degrees(Nd). There are two eta2-Ph2pz ligands on the terminal Ln atoms and one on the central metal with adjacent Ln atoms linked by one mu-eta2:eta2 and one mu-eta5 (to terminal Ln):eta2 pyrazolate group. Thus the terminal Ln atoms are formally nine-coordinate and the central Ln, ten-coordinate. By contrast, [Ln2(Ph2pz)6] (Ln = Er or Lu) complexes are dimeric with two terminal (eta2) and two bridging (mu-eta2:eta2) pyrazolates and eight-coordinate lanthanoids. All six heteroleptic complexes [Ln(Ph2pz)3(Ph2pzH)2] (Ln = La, Nd, Gd, Tb, Er or Yb) are isomorphous with three equatorial eta2-Ph2pz groups, transoid(N-Ln-N 158.18(6)-161.43(9) degrees) eta1-pyrazole ligands, and eight-coordinate Ln throughout.     

Ln3UO6Cl3 (Ln=La,Pr, Nd) -. Die ersten Oxochlorouranate der Seltenen Erden

Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) — The First Oxochlorouranates of the Rare Earths . The new compounds Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) were prepared by heating stoichiometric amounts of LnOCl/Ln₂O₃/U₃O₈ (7 : 1 : 1) (Ln=La, Nd) and PrOCl/Pr₆O₁₁/U₃O₈ (12 : 1 : 2) in silica ampoules (5 d, 1000°C, Ln=La; 9 d 800°C, Ln=Pr, Nd) in the presence of an excess of chlorine [p(Cl₂, 25°C)=1 atm]. Single crystals were obtained by chemical transport reactions using chlorine [p(Cl₂, 25°C)=1 atm] as transport agent [T₂=1000°C→T₁=900°C (Ln=La); T₂=840°C→T₁=780°C (Ln=Pr, Nd)]. Crystals of Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) were investigated by X-ray diffraction methods and La₃UO₆Cl₃ additionally by high resolution electron microscopy. The compounds Ln₃UO₆Cl₃ crystallize in the hexagonal spacegroup P6₃/m (No. 176) with Z=2 formula units per unit cell. Isotypical structure refinements resulted in R=3.04% respectively R_w=1.91% (Ln=La), R=4.72% respectively R_w=3.80% (Ln=Pr) and R=3.99% respectively R_w=2.49% (Ln=Nd). Uranium is coordinated with six oxygen atoms forming a trigonal prism. Lanthanide ions are 10-coordinated (6 oxygen atoms, 4 chlorine atoms).     

Syntheses and characterization of some mixed Te/Se polychalcogenide anions [Te(m)Se(n)]2-

Several mixed Te/Se polychalcogenide anions [Te(m)Se(n)](2-) were synthesized at 293 K by reactions between Te(n)(2-)and Se(n)(2-) anions in N,N-dimethylformamide (DMF) in the presence of different-size ammonium or phosphonium cations, in some cases in the presence of metal species. The structures of these anions were determined by single-crystal X-ray diffraction methods. The crystal structures of [NEt(4)](2)[Te(3)Se(6)] (1) and [NEt(4)](2)[Te(3)Se(7)] (2) consist, respectively, of one-dimensional infinite 1(infinity)[Te(3)Se(6)(2-)] and 1(infinity)[Te(3)Se(7)(2-)] anionic chains separated by NEt(4)(+) cations. In compound 1, each chain comprises Te(3)Se(5) eight-membered rings bridged by Se atoms. The Te(3)Se(5) ring has an "open book" conformation. The NMR spectrum of a DMF solution of [NEt(4)](2)[Te(3)Se(6)] crystals at 223 K shows (77)Se resonances at delta = 290, 349, and 771 ppm and a single (125)Te resonance at delta = 944.7 ppm. In compound 2, each chain comprises Te(3)Se(6) five- and six-membered rings bridged by Se atoms. The Te(3)Se(6) ring can be regarded as an inorganic analogue of bicyclononane. The anion of [PPh(4)](2)[Te(2)Se(2)] (4) contains a Se-Te-Te-Se chain with the terminal Se atoms trans to one another. The new compounds [PPN](2)[TeSe(10)] (3), [NMe(4)](2)[TeSe(3)].DMF (5), and [NEt(4)](2)[TeSe(3)] (6) contain known anions.     

Solvothermal syntheses of [Ln(en)3(H2O)x(mu(3-x)-SbS4)] (Ln = La, x = 0; Ln = Nd, x = 1) and [Ln(en)4]SbS4.0.5en (Ln = Eu, Dy, Yb): a systematic study on the formation and crystal structures of new lanthanide thioantimonates(V)

New lanthanide thioantimonate(V) compounds, [Ln(en)3(H2O)x(mu(3-x)-SbS4)] (en = ethylenediamine, Ln = La, x = 0, Ia; Ln = Nd, x = 1, Ib) and [Ln(en)4]SbS4.0.5en (Ln = Eu, IIa; Dy, IIb; Yb, IIc), were synthesized under mild solvothermal conditions by reacting Ln2O3, Sb, and S in en at 140 degrees C. These compounds were classified as two types according to the molecular structures. The crystal structure of type I (Ia and Ib) consists of one-dimensional neutral [Ln(en)3(H2O)x(mu(3-x)-SbS(4))]infinity (x = 0 or 1) chains, in which SbS4(3-) anions act as tridentate or bidentate bridging ligands to interlink [Ln(en)3]3+ ions, while the crystal structure of type II (IIa, IIb, and IIc) contains isolated [Ln(en)4]3+ cations, tetrahedral SbS4(3-) anions, and free en molecules. A systematic investigation of the crystal structures of the five lanthanide compounds, as well as two reported compounds, clarifies the relationship between the molecular structure and the entity of the lanthanide(III) series, such as the stability of the lanthanide(III)-en complexes, the coordination number, and the ionic radii of the metals.     

Structural and near-IR photophysical studies on ternary lanthanide complexes containing poly(pyrazolyl)borate and 1,3-diketonate ligands

The ligands tris[3-(2-pyridyl)pyrazol-1-yl]hydroborate (L1, potentially hexadentate) and bis[3-(2-pyridyl)pyrazol-1-yl]dihydroborate (L2, potentially tetradentate) have been used to prepare ternary lanthanide complexes in which the remaining ligands are dibenzoylmethane anions (dbm). [Eu(L1)(dbm)2] is eight-coordinate, with L1 acting only as a tetradentate chelate (with one potentially bidentate arm pendant) and two bidentate dbm ligands. [Nd(L1)(dbm)2] was also prepared but on recrystallization some of it rearranged to [Nd(L1)2][Nd(dbm)4], which contains a twelve-coordinate [Nd(L1)2]+ cation (two interleaved hexadentate podand ligands) and the eight-coordinate anion [Nd(dbm)4]- which, uniquely amongst eight-coordinate complexes having four diketonate ligands, has a square prismatic structure with near-perfect O8 cubic coordination. Formation of this sterically unfavourable geometry is assumed to arise from favourable packing with the pseudo-spherical cation. The isostructural series of complexes [Ln(L2)(dbm)2](Ln = Pr, Nd, Eu, Gd, Tb, Er, Yb) was also prepared and all members structurally characterised; again the metal ions are eight-coordinate, from one tetradentate ligand L2 and two bidentate dbm ligands. Photophysical studies on the complexes with Ln = Pr, Nd, Er, and Yb were carried out; all show the near-IR luminescence characteristic of these metal ions, with longer lifetimes in CD3OD than in CH3OH. For [Yb(L2)(dbm)2], two species with different luminescence lifetimes were observed in CH3OH solution, corresponding to species with zero or one coordinated solvent molecules, in slow exchange on the luminescence timescale. For [Nd(L2)(dbm)2] a single average solvation number of 0.7 was observed in MeOH. For [Pr(L2)(dbm)2] a range of emission lines in the visible and NIR regions was detected; time-resolved measurements show a particularly high susceptibility to quenching by solvent CH and OH oscillators.     

The CsLnMSe3 semiconductors (Ln = rare-earth element,Y; M = Zn,Cd, Hg)

CsLnCdSe(3) (Ln = Ce, Pr, Sm, Gd, Tb, Dy, Y) and CsLnHgSe(3) (Ln = La, Ce, Pr, Nd, Sm, Gd, Y) have been synthesized at 1123 K. These isostructural materials crystallize in the layered KZrCuS(3) structure type in the orthorhombic space group Cmcm and are group X extensions of the previously characterized Zn compounds. The structure is composed of two-dimensional [LnMSe(3)] layers that stack perpendicular to [010] and are separated by layers of face- and edge-sharing CsSe(8) bicapped trigonal prisms. Because there are no Se-Se bonds in the structure of CsLnMSe(3) (M = Zn, Cd, Hg), the formal oxidation states of Cs/Ln/M/Se are 1+/3+/2+/2-. CsSmHgSe(3) does not adhere to the Curie-Weiss law, whereas CsCeHgSe(3) and CsGdHgSe(3) are Curie-Weiss paramagnets with micro (eff) values of 2.77 and 7.90 micro (B), corresponding well with the theoretical values of 2.54 and 7.94 micro (B) for Ce(3+) and Gd(3+), respectively. Single-crystal optical absorption measurements were performed with polarized light perpendicular to the (010) and (001) crystal faces of these materials. The band gaps of the (010) crystal faces range from 1.94 eV (CsCeHgSe(3)) to 2.58 eV (CsYCdSe(3)) whereas those of the (001) crystal faces span the range 2.37 eV (CsSmHgSe(3)) to 2.54 eV (CsYCdSe(3) and CsYHgSe(3)). The largest band gap variation between crystal faces is 0.06 eV for CsYCdSe(3). Theoretical calculations for CsYMSe(3) indicate that these materials are direct band gap semiconductors whose colors and optical band gaps are dependent upon the orbitals of Y, M, and Se.     

Three-dimensional lanthanide(III)-copper(II) compounds based on an unsymmetrical 2-pyridylphosphonate ligand: an experimental and theoretical study

Based on an unsymmetrical 2-pyridylphosphonate ligand, two types of Ln(III)-Cu(II) compounds with three-dimensional structures were obtained under hydrothermal conditions, namely, Ln(2)Cu(3)(C(5)H(4)NPO(3))(6).4H(2)O (1.Ln; Ln=La, Ce, Pr, Nd) and Ln(2)Cu(3)(C(5)H(4)NPO(3))(6) (2.Ln; Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho). Compounds 1.Ln are isostructural and crystallize in chiral cubic space group I2(1)3. In these structures, each Ln ion is nine-coordinate and has a tricapped triprismatic geometry, while each Cu center is six-coordinate with an octahedral environment. The {LnO(9)} polyhedra and {CuN(2)O(4)} octahedra are connected by edge sharing to form an inorganic open framework structure with a 3-connected 10-gon (10,3) topology in which the Ln and Cu atoms are alternately linked by the phosphonate oxygen atoms. Compounds 2.Ln are isostructural and crystallize in trigonal space group R3. In these structures, the {LnO(6)} octahedra are triply bridged by the {CPO(3)} tetrahedra by corner sharing to form an infinite chain along the c axis. Each chain is connected to its six equivalents through corner sharing of {CPO(3)} tetrahedra and {CuN(2)O(2)} planes to form a three-dimensional framework structure in which the Ln and Cu atoms are linked purely by O-P-O units. The formation of these two types of structures is rationalized by quantum chemical calculations, which showed that both the lanthanide contraction and the electron configuration of Cu(II) play important roles. When Cu(II) was replaced by Zn(II), only the first type of compounds resulted. The magnetic properties of complexes 1.Ln and 2.Ln were investigated. The nature of Ln(III)-Cu(II) (Ln=Ce, Pr, Nd) interactions is illustrated by comparison with their Ln(III)-Zn(II) analogues.     

K3Ln(AsS4)2 (Ln = Nd, Sm, Gd): the first rare earth thioarsenate compounds with infinite straight (1)infinity[Ln(AsS4)2]3- chains

The structures of the novel compounds K3Ln(AsS4)2 (Ln = Nd, Sm, Gd) contain infinite straight (1)infinity[Ln(AsS4)2]3- anionic chains which are composed of interconnected LnS8 polyhedra and AsS4 tetrahedra. The compounds were synthesized via reactions of Ln metals with in-situ-formed potassium polythioarsenate fluxes.     

Direct solvothermal growth, crystal structures, and optical properties of one-dimensional lanthanide selenidoarsenate(v) polymers [Ln(dien)2(micro3-AsSe4)] (Ln = Nd, Sm): the first example of an AsSe4(3-) anion acting as a ligand to a lanthanide complex

Two novel lanthanide selenidoarsenates(v) [Ln(dien)2(micro(3)-AsSe(4))] (Ln = Nd 1, Sm 2, dien = diethylenetriamine) were synthesized by the reactions of As(2)O(3) and Se with Nd(2)O(3) or Sm(2)O(3) in dien under solvothermal conditions. 1 and 2 are in the orthorhombic crystal system with Iba2 and Pbca space groups, respectively. The [AsSe(4)](3-) anion acts as a tridentate micro(3)-AsSe(4) ligand to bridge the lanthanide [Ln(dien)2](3+) complexes leading to one-dimensional neutral [Ln(dien)(2)(micro(3)-AsSe(4))](infinity) chains. The chains contact through hydrogen bonding to form network structures. The lanthanide center lies within a nine-coordinated environment involving six N atoms of two dien ligands and three Se atoms of two different tetrahedral [AsSe(4)](3-) anions forming a distorted monocapped square antiprism. The novel coordination polymers [Nd(dien)2(micro(3)-AsSe(4))](infinity) and [Sm(dien)2(micro(3)-AsSe(4))](infinity) are the first examples of solvothermally synthesized selenidoarsenates with [AsSe(4)](3-) anion acting as a ligand in lanthanide complexes. The band gaps of 2.11 eV for 1, and 2.18 eV for 2 have been derived from optical absorption spectra. TG-DSC curves show that two compounds remove coordinated dien ligands in a single step.