13813-23-5Relevant articles and documents
A section through the compositional triangle Pr-Co-I at 600 °C: Pr 7CoI12 and Pr2Co2I
Palasyuk, Andriy,Pantenburg, Ingo,Meyer, Gerd
, p. 1969 - 1971 (2006)
At 600 °C, two phases exist in equilibrium in the system Pr-Co-I, Pr7CoI12 and Pr2Co2I, the former with isolated {Pr6Co} clusters, the latter with Pr-Co-Pr slabs. The crystal structures were determined from single-crystal X-ray data: Pr 7CoI12: trigonal, R3 (no. 148), a = 1581.62(10), c = 1079.18(7) pm, Z = 3, R = 0.0493 for all data; Pr2Co2I: hexagonal, P63/mmc (no. 194), a = 403.86(4), c = 1743.4(2) pm, Z = 2. R = 0.1196 for all data.
A three dimensional network of iodide ions and iodine molecules in the crystal structure of [Pr(benzo-15-crown-5)2]I21
Pantenburg, Ingo,Mueller, Ingrid
, p. 1637 - 1640 (2004)
Black polyhedra of [Pr(benzo-15-crown-5)2]I21 were grown from an ethanol / dichlormethane solution of PrI3, benzo-15-crown-5 and I2. The crystal structure (orthorhombic, P2 1cn, a = 1201.1(1), b = 2168.3(1), c = 2571.1(1) pm, Z = 4) is built up from sandwich like cations [Pr(benzo-15-crown-5)2]3+ and polyiodide anions I213-. This unique polyiodide anion exhibits a complex connection pattern of iodide ions and iodine molecules with variable bond lengths forming a complicated network.
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.
The extended chain compounds Ln12(C2)3I17 (Ln=Pr, Nd, Gd, Dy): Synthesis, structure and physical properties
Ryazanov, Mikhail,Mattausch, Hansjuergen,Simon, Arndt
, p. 1372 - 1380 (2008/10/09)
The title compounds are obtained in high yield from stoichiometric mixtures of Ln, LnI3 and graphite, heated at 900-950 °C in welded Ta containers. The crystal structures of new Pr and Nd phases determined by single-crystal X-ray diffraction are related to those of other Ln12(C2)3I17-type compounds (C 2/c, a=19.610(1) and 19.574(4) A, b=12.406(2) and 12.393(3) A, c=19.062(5) and 19.003(5) A, β=90.45(3)° and 90.41(3)°, for Pr12(C2)3I17 and Nd12(C2)3I17, respectively). All compounds contain infinite zigzag chains of C2-centered metal atom octahedra condensed by edge-sharing into the [tcc]∞ sequence (c=cis, t=trans) and surrounded by edge-bridging iodine atoms as well as by apical iodine atoms that bridge between chains. The polycrystalline Gd12(C2)3I17 sample exhibits semiconducting thermal behavior which is consistent with an ionic formulation (Ln3+)12(C26-)3(I-)17(e-) under the assumption that one extra electron is localized in metal-metal bonding. The magnetization measurements on Nd12(C2)3I17, Gd12(C2)3I17 and Dy12(C2)3I17 indicate the coexistence of competing magnetic interactions leading to spin freezing at Tf=5 K for the Gd phase. The Nd and Dy compounds order antiferromagnetically at TN=25 and 29 K, respectively. For Dy12(C2)3I17, a metamagnetic transition is observed at a critical magnetic field H≈25 kOe.
The enthalpies of formation of praseodymium halides PrCl3, PrBr3, and PrI3 in the crystalline state and aqueous solution
Goryushkina,Monaenkova,Popova,Tiflova
, p. 1710 - 1713 (2007/10/03)
The enthalpies of solution of praseodymium tribromide and triiodide in water were measured at 298.15 K in a hermetic isothermic-shell swinging calorimeter. The data obtained and the Δf H° (Pr 3+, sln, ∞H2O, 298 K) value found earlier were used to calculate the enthalpies of formation of three praseodymium halides (PrCl3, PrBr3, and PrI3) in the crystalline state and aqueous solution. Nauka/Interperiodica 2006.
Pr4N2S3 and Pr4N 2Se3: Two non-isostructural praseodymium(III) nitride chalcogenides
Lissner, Falk,Schleid, Thomas
, p. 427 - 432 (2008/10/09)
The non-isostructural nitride chalcogenides of praseodymium, Pr 4N2S3 and Pr4N2Se 3, are formed by the reaction of the praseodymium metal with sodium azide (NaN3), praseodymium trihalide (PrX3; X = Cl, Br, I) and the respective chalcogen (sulfur or selenium) at 900°C in evacuated silica ampoules after seven days. Both crystallize monoclinically in space group C2/c (Pr4N2S3: a = 1788.57(9), b = 986.04(5), c = 1266.49(6) pm, β = 134.546(7)°, Z = 8; Pr4N 2Se3: a = 1311.76(7), b = 1017.03(5), c = 650.42(3) pm, β = 90.114(6)°, Z = 4). The crystal structures of both compounds show a layered construction, dominated by N3--centred (Pr 3+)4 tetrahedra which share a common edge first. Continuing linkage of the so resulting bitetrahedral [N2Pr 6]12+ units via the non-connected vertices to layers according to ∞2{[N(Pr)2/2 e(Pr')2/2v]3+} forms different kinds of tetrahedral nets which can be described as layers consisting of four- and eight-rings for Pr4N2S3 and as layers of six-rings for Pr4N2Se3. Whereas the crystal structure of Pr4N2S3 exhibits four different Pr3+ cations with coordination numbers of six (2x) and seven (2x) against N3- and S2-, the number of cations in the nitride selenide (Pr4N2Se3) is reduced to half (Pr1 and Pr2) also having six- and sevenfold anionic coordination spheres. Further motifs for the connection of [NM4]9+ tetrahedra in crystal structures of nitride chalcogenides and halides of the rare-earth elements with ratios of N:M = 1:2 are presented and discussed.
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
Rare earth iodide complexes of 4-formyl-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one
Joseph, Siby,Radhakrishnan
, p. 1219 - 1229 (2008/10/09)
Rare earth complexes of 4-formyl-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one (FDPP) having the general formula [Ln(FDPP)4I2]I, where Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Dy, Ho and Er, have been synthesised and characterised by elemental analyses, molar conductance in non-aqueous solvents, electronic, infrared and proton NMR spectra as well as thermogravimetric analyses. FDPP acts as a neutral monodentate ligand coordinating through the ring carbonyl oxygen. Two of the iodide ions are coordinated. A coordination number of six may be assigned to the metal ion in these complexes. The covalency parameters evaluated from the solid state electronic spectra suggest weak covalent character of the metal-ligand bond. The TG data of the lanthanum complex indicate that the complex is stable up to about 140° C and undergoes decomposition in three stages forming lanthanum oxide as the final product.
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.
