Structure and stereochemistry in 'f-block' complexes of high coordination number. VIII. The [M(unidentate)9] system. Crystal structures of [M(OH2)9] [CF3SO3]3, M = La, Gd, Lu, Y

1983 ◽  
Vol 36 (3) ◽  
pp. 483 ◽  
Author(s):  
JM Harrowfield ◽  
DL Kepert ◽  
JM Patrick ◽  
AH White
Keyword(s):  
Rare Earth ◽  
Crystal Structures ◽  
Ethyl Sulfate ◽  
Rare Earth Atom ◽  
Repulsion Energy ◽  
High Coordination Number ◽  
Tricapped Trigonal Prism ◽  
Cell Dimensions ◽  
High Coordination ◽  
The Rare Earth

The crystal structures of the nonahydrates of the rare earth trifluoromethanesulfonates, [M(OH2)9] [CF3SO3]3 have been determined at 295 K for the configurations fO, f7, f14, i.e. M = La, Gd, Lu, together with that of the yttrium analogue. The structures are similar to those of the rare earth ethyl sulfate nonahydrates, belonging to space group P6,/m (hexagonal) with cell dimensions a ≈ 13.7, c ≈ 7.5 �, Z 2, with the coordination about the rare earth atom being a tricapped trigonal prism. The structure is compared with that found from repulsion energy calculations.

Structure of Rare-earth/Alkali Halide Complexes

2001 ◽  
Vol 56 (11) ◽  
pp. 721-724 ◽  
Author(s):  
Z. Akdeniz ◽  
Z. Çiçek Önem ◽  
M. P. Tosia
Keyword(s):  
Rare Earth ◽  
Alkali Halide ◽  
Elevated Temperatures ◽  
Alkali Halides ◽  
Energy Difference ◽  
Alkali Atom ◽  
Complexing Agent ◽  
Coordination State ◽  
Rare Earth Atom ◽  
The Rare Earth

Abstract Vapour complex formation of rare-earth halides with alkali halides strongly increases the volatility of these compounds. We evaluate the structure taken by such complexes having the chemical formulas MRX4, M2RX5 and M3RX6, where X = F or Cl and typically M = Li or Na and R = La. The roles played by the two types of metal atom is investigated in MRX4 complexes by also taking M = K, Rb or Cs and R = Gd or Lu. The main predictions that emerge from our calculations are as follows: (i) in MRX4 a fourfold coordination of the rare-earth atom is accompanied by twofold or threefold coordination of the alkali atom, the energy difference in favour of the twofold-coordination state being about 0.3 eV in the case of the LiF complexing agent but even changing sign as the ionic radius of either the alkali or the halogen is increased; (ii) in M2RX5 a fivefold coordination of the rare-earth atom is energetically more stable than a fourfold one, by again not more than about 0.3 eV; (iii) in M3RX6 the fivefold and sixfold coordinations of the rare-earth atom are energetically competitive; and (iv) in both M2RX5 and M3RX6 each coordination state can be realized in various forms that differ in detail but are close in energy. Bond fluctuations and disorder around the rare-earth atom can be expected to be a general feature at elevated temperatures, both in the vapour and in liquid rare-earth/alkali halide mixtures.

scholarly journals Darstellung und Struktur ternärer Silizide und Germanide des Lithiums mit den Seltenen Erden Y und Gd im Fe2P-Typ / Preparation and Crystal Structure of Ternary Silicides and Germanides of Lithium with the Rare-Earth-Metals Y and Gd in the Fe2P-Type Structure

1979 ◽  
Vol 34 (8) ◽  
pp. 1057-1058 ◽  
Author(s):  
Axel Czybulka ◽  
Günter Steinberg ◽  
Hans-Uwe Schuster
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Crystal Structures ◽  
Rare Earth Metals ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
P Type ◽  
Type Lattice ◽  
The Rare Earth

In the systems Li-M-X = (M = Y, Gd; X = Si, Ge) the compounds LiYSi, LiYGe and LiGdGe were prepared. Their crystal structures were determined by X-ray investigations. They crystallize hexagonally (space group P 6̄2m), and a C22-(Fe2P-type) lattice was found

scholarly journals Flux Synthesis, Crystal Structures, and Magnetic Ordering of the Rare-Earth Chromium(II) Oxyselenides RE2CrSe2O2 (RE = La–Nd)

2017 ◽  
Vol 56 (4) ◽  
pp. 2241-2247 ◽  
Author(s):  
Simon Peschke ◽  
Valentin Weippert ◽  
Anatoliy Senyshyn ◽  
Martin Johann Mühlbauer ◽  
Oliver Janka ◽  
...  
Keyword(s):  
Rare Earth ◽  
Crystal Structures ◽  
Magnetic Ordering ◽  
Flux Synthesis ◽  
The Rare Earth

Structure of Rare-earth/Group-IIIA Chloride Complexes

2002 ◽  
Vol 57 (12) ◽  
pp. 937-942 ◽  
Author(s):  
Z. Çiçek Önem ◽  
Z. Akdeniz ◽  
M. P. Tosia
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Coulomb Field ◽  
Coordination Shell ◽  
Rare Earth Ion ◽  
Chloride Complexes ◽  
Model Calculations ◽  
High Coordination ◽  
The Rare Earth

We evaluate the structures taken by vapour complexes of chloride compounds with the chemical formula MnRCl3(n+1) where R is a selected rare-earth element, M a group-IIIA element, and n = 1, 2, or 3. The main predictions that emerge for the most stable structures from our model calculations are as follows: (i) in MRCl6 a fivefold coordination of the rare-earth element (for R = La, Nd, Er, or Lu) is very stable relative to a fourfold one, with the excess binding energy decreasing slightly from La to Lu and being almost the same when M = Al or Ga; (ii) a sixfold coordination of Nd becomes very stable in Ga2NdCl9; and (iii) sevenfold and eightfold coordinations of Nd can arise in Ga3NdCl12, with the latter being more stable. All these structures are obtained from the RCl3 monomer by substituting n chlorines with n MCl4 distorted tetrahedra, which complete the coordination shell of the rare-earth ion via edge or face-sharing. This criterion combines high coordination of the rare-earth ion with shielding of its Coulomb field by bonding chlorines in double or triple sets. The possible appearance of the unusual fivefold and sevenfold coordination states in the vapour complexes should provide further motivation for experimental structural studies and for refined quantum-chemical calculations

scholarly journals The crystal structures of the rare earth binary gallides

1984 ◽  
Vol 40 (a1) ◽  
pp. C243-C243
Author(s):  
E. I. Hladyshevsky ◽  
Ya. P. Yarmolyuk ◽  
Yu. N. Hryn
Keyword(s):  
Rare Earth ◽  
Crystal Structures ◽  
The Rare Earth

Crystal structures of rare earth elements rich apatite analogues

1990 ◽  
Vol 191 (3-4) ◽  
Author(s):  
Nicoline Kalsbeek ◽  
Sine Larsen ◽  
Jørn G. Rønsbo
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
Hexagonal System ◽  
Space Group ◽  
X Ray ◽  
Cell Dimensions

AbstractThe crystal structures have been determined for britholite-(Ce) and lessingite-(Ce) from the type localities and a third sample (‘min X’) showing chemical similarities to both britholite-(Ce) and lessingite-(Ce). This sample is from the Ilímaussaq intrusion in Greenland. They are rare earth elements (REE) rich apatite analogues. Based on the X-ray diffraction results they were assigned to the hexagonal system with cell dimensions slightly larger than those of apatite. The three structures have been refined in the space group

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