- Condensed double-chain cluster complexes with seven-coordinate endohedral iridium atoms in {Ir2Gd5}Br5
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The new condensed double-chain cluster complex compound {Ir 2Gd5}Br5 was obtained from a reaction of GdBr3 with metallic gadolinium and iridium at elevated temperatures. The thin black needles crystallize with the orthorhombic crystal system, space group Pnma(no. 62); a = 1255.4(1) pm, b = 414.05(3) pm, c = 2633.8(3) pm,Z = 4, R1/wR2 = 0.0504/0.0346 for all data. Monocapped trigonal prisms of gadolinium atoms with endohedral iridium atoms are connected by common rectangular faces to chains and further by edges to double chains, which form a herringbone arrangement. The double chains are coordinated by bromido ligands and are connected in accord with the formulation {Ir2Gd 5}Br4/2iBr2/3i(e)Br 1/3i(f)Br2/2i-i(e/f)Br 1/2i-aBr1/2a-i. Copyright
- Bruehmann, Matthias,Meyer, Gerd
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- Quenching of the Luminenscence of the Aqueous Gadolinium Ion by Nitrate and Thiocyanate
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The emission from the lowest sextet of the aqueous gadolinium ion is found to be strongly quenched by nitrate and thiocyanate.The influence of ionic strength, temperature, viscosity and a strong complexing agent such as EDTA, have been investigated.Quenching occurs by an electron-exchange energy-transfer mechanism.
- Vuilleumier, Jean-Jacques,Deschaux, Michel,Marcantonatos, Minas D
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- Structural characterization of methanol substituted lanthanum halides
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The first study into the alcohol solvation of lanthanum halide [LaX3] derivatives as a means to lower the processing temperature for the production of the LaBr3 scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(μ-Br)(H2O)7](Br)2}2 (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H2O)7(MeOH)2](Br)3 (2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH2, crystals of [Ca(MeOH)6](Br)2 (3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr2.75·5.25(MeOH)]+0.25 [LaBr3.25·4.75(MeOH)]-0.25} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr3 in MeOH forming the 8-coordinated [LaBr3(MeOH)5] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX3 derivatives were isolated as [(MeOH)4(Cl)2La(μ-Cl)]2 (6) and [La(MeOH)9](I)3·MeOH (7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR (139La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4-6 were slightly higher in comparison to their hydrated counterparts.
- Boyle, Timothy J.,Ottley, Leigh Anna M.,Alam, Todd M.,Rodriguez, Mark A.,Yang, Pin,Mcintyre, Sarah K.
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p. 1784 - 1795
(2010/07/03)
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- Systematics and anomalies in rare earth/aluminum bromide vapor complexes: Thermodynamic properties of the vapor complexes LnAl3Br12 from Ln = Sc to Ln = Lu
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Systematics and anomalies in the rare earth/aluminum bromide vapor complexes have been investigated by the phase equilibrium-quenching experiments. The measurements suggest that the LnAl3Br12 complexes are the predominant vapor compl
- Wang, Zhi-Chang,Yu, Jin
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p. 4248 - 4255
(2008/10/09)
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- New layered germanide halides RE2GeX2 (RE = Y, Gd; X = Br, I)
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The title compounds were synthesized from RE, REX3, and Ge under an Ar atmosphere at 1200-1370 K. Y2GeI2 and Gd 2GeI2 crystallize in space group R3m with lattice constants a = 4.2135(3) and 4.2527(1) A and c = 31.480(2) and 31.657(1) A, respectively. Gd2GeBr2 crystallizes in two modifications, the 1T-type (space group P3m1; a = 4.1668(2) A, c = 9.8173(6) A) and the 3R-type (space group R3m; a = 4.1442(9) A, c = 29.487(7) A). The structural motifs of RE2GeX2 compounds are Ge-centered slightly distorted RE6 octahedra connected via their common edges and extending in the a and b directions. The resulting close-packed double layers are separated by halogen atoms. The electrical resistivity measurements revealed semiconductor behavior for Y 2GeI2 and Gd2GeI2 and a metal-semiconductor transition for 1T-Gd2GeBr2. Magnetic susceptibility and heat capacity measurements show long-range magnetic ordering for Gd2GeI2 and 1T-Gd2GeBr2 at ~15 and ~13 K, respectively.
- Lukachuk, Mar'yana,Kremer, Reinhard K.,Mattausch, Hansjuergen,Simon, Arndt
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p. 3231 - 3235
(2008/10/09)
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- M3NS3 (M = La - Nd, Sm, Gd - Dy): Structure and magnetism of 3:1:3-type nitride sulfides of trivalent lanthanides
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Nitride sulfides of the trivalent lanthanides with the composition M 3NS3 (M = La - Nd, Sm, Gd - Dy) can be prepared by the oxidation of the respective lanthanide metal with sulfur, sodium azide (NaN 3), and the corresponding lanthanide tribromide (MBr3) when an additional flux (NaBr) is used. Temperature ranges from 800 to 900 °C for the thermal treatment of the reaction mixtures in evacuated silica tubes secure the formation of bright to dark brown, transparent, lath shaped single-crystals. The orthorhombic crystal structure (Pnma, Z = 4) was determined from single-crystal X-ray diffraction data (La3NS3: a = 1215.13(5), b = 415.90(2), c = 1322.12(5) pm, Ce3NS3: a = 1206.28(4), b = 410.16(1), c = 1307.18(5) pm, Pr3NS3: a = 1205.45(7), b = 405.35(2), c = 1297.58(8) pm, Nd3NS3: a = 1207.82(5), b = 401.31(1), c = 1295.20(4) pm, Sm3NS3: a = 1201.58(6), b = 394.84(2), c = 1285.63(7) pm, Gd3NS3: a = 1197.17(7), b = 388.22(3), c = 1286.92(8) pm, Tb3NS3: a = 1191.62(7), b = 385.07(3), c = 1282.44(8) pm, and Dy3NS3: a = 1187.66(7), b = 382.55(3), c = 1276.77(8) pm). There are three crystallographically different M3+ cations present in coordination of both the N3- and the S2- anions. However, [NM 4]9+ tetrahedra connected via two common corners (c) to form linear chains ∞1{[N(M1)1/1 t(M2)1/1t(M3)2/2c] 6+} along [010] build up the main structural feature. A non-linear behaviour for the decreasing lattice constants of the pseudo-isotypic series from La3NS3 to Dy3NS3 concerning the a- and c-axes is observed along with the lanthanoid contraction caused by the diminishing coordination sphere of (M1)3+ (CN = 7) and (M3) 3+ (CN = 7) moving from the light to the heavier lanthanides. Curie-Weiss-type magnetic behaviour for Dy3NS3 with μeff = 10.3(1) μB for DyN1/3S corresponding to a 6H15/2 groundstate for Dy3+ at higher temperatures and antiferromagnetic ordering of the Dy3+ moments below 5 K is observed.
- Lissner, Falk,Meyer, Monika,Kremer, Reinhard K.,Schleid, Thomas
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p. 1995 - 2002
(2008/10/09)
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- Gd10I16(C2)2 and Gd10Br15B2/Tb10Br15B 2 cluster compounds with M10 twin octahedra
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The compound Gd10I16(C2)2 can be prepared from Gd metal, GdI3 and C at 950 °C. It crystallizes in P1? with a = 10.463(4) A?, b = 16.945(6) A?, c = 11.220(4) A?, α = 99.15(3)°, β = 92.68(3)° und γ = 88.06(3)°. Gd10Br15B2 is formed between 900 und 950 °C, Tb10Br15B2 between 900 und 930 °C from stoichiometric amounts of the rare earth metals, tribromide and boron. Both compounds crystallize in the space group P1? for Gd10Br15B2 with a = 8.984(2) A?, b = 9.816(2) A?, c = 10.552(5) A?, α = 91.14(3)°, β = 114.61(3)° and γ = 110.94(3)° and for Tb10Br15B2 with a = 8.939(4) A?, b = 9.788(3) A?, c = 10.502(2) A?, α = 91.19(3)°, β = 114.51(3)° and γ = 111.10(2)°. In the crystal structures of all three compounds the rare earth metals form edge-shared Ln10 twin octahedra. In Gd10I16(C2)2 the Gd octahedra are centered with C2 groups (dC-C = 1.43(7) A?). In Ln10Br15B2 (Ln = Gd, Tb) the octahedra contain single boron atoms. The clusters are connected through halide atoms to chains [Ln10(Z)2Xi4Xi-i 4/2Xi-a2]. Adjacent chains are fused threedimensionally via Ii-a2Ii-a6 for the Gd iodide carbide and via Bri-i2/2Bri-a6 for the bromide borides of Gd und Tb. It is interesting to see an identical pattern of connection between the chains for the reduced oxomolybdates, e. g. PbMo5O8.
- Mattausch, Hansju?rgen,Warkentin, Eberhard,Oeckler, Oliver,Simon, Arndt
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p. 2117 - 2124
(2008/10/08)
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- COMPLEXES OF YTTRIUM AND LANTHANIDE BROMIDES WITH 4-N-(2'-HYDROXYBENZYLIDENE)AMINOANTIPYRINEY
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Ten new complexes of bromides of yttrium and lanthanides with 4-N-(2'-hydroxybenzylidene)aminoantipyrine (HBAAP) having the formula [Ln(HBAAP)2Br2]Br, where Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho and Er have been prepared and characterized. Molar conductance studies indicate 1:1 electrolytic behaviour for these complexes. Their infrared spectra show that HBAAP acts as a neutral tridentate ligand coordinatin throuhg the carbonyl oxzgen, azomethine nitrogen and phenolic oxygen. Electronic spectra showthe week covalent character in the metal-ligand bond. Thermogravimetric studies indicate that these complexes are stable up to about 170.degree .C and undergo decomposition in two stages forming the respective metal bromides as the final products.
- Joseph, M.,Nair, M. K. M.,Radhakrishnan, P. K.
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p. 1331 - 1344
(2008/10/09)
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- X-RAY POWDER DIFFRACTION STUDY OF THE CHLORIDE-BROMIDE SYSTEMS OF TRIVALENT GADOLINIUM, TERBIUM, AND YTTERBIUM.
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The lanthanoid mixed halide systems, MCl//3-MBr//3, for M equals Gd, Tb, and Yb, have been prepared by mixing and fusing the pure reactants and have been examined by X-ray powder diffraction procedures. For M equals Gd, UCl//3, (P6//3/m)-, PuBr//3 (Cmcm)-
- Olejak-Chodan, Monika,Lasocha, Wieslaw,Eick, Harry A.
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p. 259 - 267
(2008/10/08)
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