7790-87-6Relevant articles and documents
Disorder in rare earth metal halide carbide nitrides
Schaloske, Manuel C.,Kienle, Lorenz,Mattausch, Hansjuergen,Duppel, Viola,Simon, Arndt
, p. 4049 - 4056 (2011)
Single-crystal X-ray structure determinations of Ce4I 6CN and disordered Ce6I9C2N phases are described together with electron-microscopy studies of Ce6I 9C2N and Y6I9C2N. Ce 4I6CN crystallizes in the tetragonal space group P4 2/mnm with a = 13.877(2) A, c = 9.665(2) A. Compounds β′-Ce6I9C2N and β″- Ce6I9C2N crystallize in space group P6/m with a = 41.774(6) A, c = 13.719(3) A and a = 20.958(3) A, c = 13.793(3) A, respectively. The main structural feature of these compounds are rods of RE6C2 octahedra and RE4N tetrahedra (RE = lanthanide) interconnected in different sequences. These rods are linked into Kagome-type frameworks with additional rods located in the centres of thehexagonal channels. The disorder patterns for these additional rods can be rationalized in terms of nearest-neighbour interactions.
Structural characterization of methanol substituted lanthanum halides
Boyle, Timothy J.,Ottley, Leigh Anna M.,Alam, Todd M.,Rodriguez, Mark A.,Yang, Pin,Mcintyre, Sarah K.
, p. 1784 - 1795 (2010/07/03)
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.
Lanthanide(III) halides: Thermodynamic properties and their correlation with crystal structure
Rycerz,Gaune-Escard
, p. 167 - 174 (2008/10/09)
Temperatures and enthalpies of phase transitions of 17 lanthanide(III) halides determined experimentally are reported. Correlations were made between temperature of fusion of lanthanide(III) halides, on the one hand, and enthalpy of fusion, on the other, versus atomic number of lanthanide. According to this classification, the lanthanide(III) halides split into groups, as also do the corresponding crystal structures. A correlation between the crystal structure of lanthanide(III) halides and their respective entropy of fusion (or entropy of fusion + entropy of solid-solid phase transition) was inferred from the aforementioned features. Fusion in those halides with hexagonal, UCl3-type and orthorhombic, PuBr3-type, structures entails an entropy of fusion change (or entropy of fusion + entropy of solid-solid phase transition change) by 50 ± 4 J mol-1 K-1. The homologous entropy change within the group of halides having the rhomboedric, FeCl3-type, structure, is smaller and equals 40 ± 4 J mol-1 K-1. Halides with monoclinic, AlCl3-type, crystal structure constitute a third group associated to an even smaller entropy change upon fusion, only 31 ± 4 J mol-1 K-1. The halides with lower entropies of fusion also have a lower S1300 K - S298 K indicating either a higher degree of order in the liquid or a higher entropy in the solid at room temperatures.
RE2+xI2M2+y (RE = Ce, Gd, Y; M = Al, Ga): Reduced rare earth halides with a hexagonal metal atom network
Lukachuk, Mar'yana,Zheng, Chong,Mattausch, Hansjürgen,Banks, Michael G.,Kremer, Reinhard K.,Simon, Arndt
, p. 633 - 641 (2008/09/21)
The title compounds were synthesized from RE, REI3 (RE = Ce, Gd, Y) and Al or Ga under an Ar atmosphere at 930-950 °C. The non-stoichiometric Ce2+xI2Al2+y and Ce 2+xI2Ga2+y compounds crystallize in the space group R3?m (No. 166) with lattice constants a = 4.3645(3), c = 35.914(2) A? for the Al and a = 4.3009(2), c = 35.680(4) A? for the Ga compound. Excess electron density found in the Wyckoff position 3a could be due to a fractional occupation by Ce or M (x = 0.06, y = 0 or x = 0, y = 0.11 in the case of the Ga_compound). The stoichiometric Gd2I2Ga 2 and Y2I2Ga2 compounds crystallize in the space group P3?m1 (No. 164) with lattice constants a = 4.1964(1) and 4.1786(7) A?, c = 11.4753(4) and 11.434(2) A?, respectively. Their structures feature M-centered (M = Al, Ga) RE trigonal prisms condensed via common rectangular faces. The electronic origin of the surplus of metal atoms in the octahedral voids between the I-layers of the Ce compounds was explored via extended Huckel-type calculations. Magnetic susceptibility, electrical resistivity and heat capacity measurements have also been carried out. These reveal a metal-insulator transition of Gd2I2Ga2 at 40 K.
Isolated and edge-sharing interstitially stabilized metal tetrahedra {M4Z} in La4ZBr7, M9Z 4I16, and BaM4Z2I8 (M = La,Ce). The nature of Z
Gerlitzki, Niels,Hammerich, Stefanie,Pantenburg, Ingo,Meyer, Gerd
, p. 2024 - 2030 (2008/10/09)
Metallothermic reductions of LaBr3, LaI3 and CeI 3 with barium metal resulted in single crystals of La 4ZBr7, M9Z4I16 and BaM4Z2I8 (M = La,Ce) as by-products, subject to apparently ubiquitous oxygen and/or nitrogen (= Z) impurities. The crystal structure of La4ZBr7 (1, orthorhombic, Pnma, Z = 4, a = 1212.4(1), b = 1404.8(2), c = 804.7(1) pm, R 1 = 0.0358 for I>2σI with N:O = 0.91:0.09) is determined by isolated {La4Z} tetrahedra surrounded by and connected through bromide ligands. In the crystal structure of Ce9Z4I 16 (2, orthorhombic, Fddd, Z = 8, a = 890.0(1), b = 2264.1(2), c = 4279.5(4) pm, R1 = 0.0262 for I>2σI with N:O = 0.75:0.25), {Ce4Z} tetrahedra are connected to {Ce4/2Z} chains via common edges and further to layers by iodide ligands. The layers are stacked and connected via the ninth cerium atom according to Ce[{Ce4/2Z}I 4]4. Similar {La4/2Z} chains and BaI 8/4 chains run perpendicularly to each other and are connected via common iodide ions in the crystal structure of BaLa4Z 2I8 = Ba2[{La4/2Z}I 4]4 (3, monoclinic, C2/c, Z = 4, a = 897.5(1), b = 2162.4(3), c = 1229.3(2), β = 110.32(1)°, R1 = 0.0261 for I>2σI with N:O = 0.54:0.46). The nature of the interstitial Z, oxygen and/or nitrogen, is evaluated.
The distinct affinity of cyclopentadienyl ligands towards trivalent uranium over lanthanide ions. Evidence for cooperative ligation and back-bonding in the actinide complexes
Mehdoui, Thouraya,Berthet, Jean-Claude,Thuery, Pierre,Ephritikhine, Michel
, p. 1263 - 1272 (2007/10/03)
The mono and bis(cyclopentadienyl) compounds [M(C5H 4But)I2] and [M(C5H 4But)2I] (M = U, La, Ce, Nd) were formed in thf by comproportionation reactions of [M(C5H4Bu t)3] and LnI3 or [UI3(L) 4] (L = thf or py) in the molar ratio of 1 : 2 and 2 : 1, respectively, while treatment of [UI3(py)4] or LnI 3 (Ln = La, Ce, Nd) with 1 or 2 mol equivalents of LiC 5H4But in thf afforded the [M(C 5H4But)I2] and [M(C 5H4But)2I2]- compounds, respectively. The X-ray crystal structures of [M(C5H 4But)I2(py)3] (M = U, La, Ce, Nd), [{Ce(C5H4But)2(μ-I)}2] and [M(C5H4But)2I(py)2] (M = U, Nd) have been determined; the differences between the average M-C distances in the mono(cyclopentadienyl) complexes correspond to the variation in the ionic radii of the trivalent uranium and lanthanide ions while the U-N and U-I bond lengths seem to be smaller than those predicted from a purely ionic bonding model. The distinct affinity of the cyclopentadienyl ligands towards Ln(III) and U(III) was revealed by two series of competing reactions: the ligand exchange reactions between [Ln(C5H4Bu t)n′I3-n′] (Ln = La, Ce, Nd) and [U(C5H4But)n′I 3-n′] species (1 ≤ n′ + n′ = n ≤ 5), and the addition of n mol equivalents of LiC5H4But (1 ≤ n ≤ 5) to a 1: 1 mixture of LnI3 and [UI 3(thf)4] or [UI3(py)4]. The stability of the [M(C5H4But)I2] species was found to vary in the order Nd > Ce > U > La, a trend which is in accord with an electrostatic bonding model. However, the bis and tris(cyclopentadienyl) complexes of uranium are more stable than their lanthanide analogues. This difference can be accounted for by a higher degree of covalency in the U-C5H4But bond, resulting from the late appearance of back-bonding which would emerge only after the first cyclopentadienyl ligand is bound. The Royal Society of Chemistry 2005.
On the reactivity of lanthanide iodides LnIx (x < 3) formed in the reactions of lanthanide metals with iodine
Khoroshenkov,Petrovskaya,Fedushkin,Bochkarev
, p. 699 - 702 (2008/10/08)
The reduced lanthanide iodides of the composition LnIx (Ln = Sc, Y, La, Ce, Pr, Gd, Ho, and Er; x 3) were obtained by the reaction of an excess of the appropriate metal with iodine at high temperatures. The diamagnetism of the Sc, Y, and La d
Planar B4 rhomboids: The rare earth boride halides RE4X5B4
Mattausch,Simon,Felser
, p. 9951 - 9957 (2007/10/03)
The new compounds RE4X5B4 (RE = La, Ce, Pr, Gd and X = Br, I) and RE4I5B2C (RE = La, Ce) are prepared via the reaction of RE metal, REX3 and B, or B and C at temperatures 1670 ≥ T ≥ 1270 K in welded tantalum ampoules. Chains of interconnected B4 rhomboids are the characteristic features of the crystal structures. According to band structure calculations, the compounds are one-dimensional metals which undergo a gradual metal-to-semiconductor transition at low temperature as experimentally indicated by the steep inrease of electrical resistivity.
Generation and Reactivities of Organocerium Reagents
Imamoto, Tsuneo,Kusumoto, Tetsuo,Yokoyama, Masataka
, p. 1042 - 1044 (2007/10/02)
Organocerium reagents, prepared in situ by the treatment of organolithium compounds with cerium(III) iodide, exhibit characteristic reactivities toward ketones; at -65 deg C, nucleophilic additions give the corresponding tertiary alcohols in excellent yields; while, at 0 deg C to ca. room temperature, reductive coupling and/or reduction of the ketones prevail.
