scholarly journals Crystal structure of K3EuSi2O7

Author(s):  
Sabina Kovac ◽  
Predrag Dabic ◽  
Aleksandar Kremenovic

As a part of the research of the flux technique for growing alkali rare-earth elements (REE) containing silicates, tripotassium europium disilicate, K3EuSi2O7, has been synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in the space group P63/mcm. In the crystal structure of the title compound, one part of the Eu cations are in a slightly distorted octahedral coordination and the other part are in an ideal trigonal prismatic coordination environment. The disilicate Si2O7 groups connect four EuO6 octahedra and one EuO6 trigonal prism. Three differently coordinated potassium cations are located between them. Silicates containing the larger rare earth elements usually crystallize in a structure that contains the rare-earth cation in both a slightly distorted octahedral and an ideal trigonal prismatic coordination environment.

1988 ◽  
Vol 133 ◽  
Author(s):  
C. T. Liu ◽  
J. A. Horton ◽  
D. G. Petitifor

ABSTRACTRare-earth elements including Y, Er and Sc were added to AlTi3 for stabilizing the Ll2 ordered crystal structure, as predicted by the AB3 structure map. The crystal structure and phase composition in the AlTi3 alloys were studied by electron microprobe analysis, X-ray diffraction and TEM. The solubility limit of the rare-earth elements were determined and correlated with the atomic size factor. The results obtained so far indicate that rare-earth additions are unable to change the crystal structure of AlTi3 from DO19 to Ll2. The inability to stabilize the Ll2 structure demonstrates the need to characterize the structure map domains with a further period-dependent parameter.


2006 ◽  
Vol 62 (4) ◽  
pp. m738-m740 ◽  
Author(s):  
Gui-Ying Dong ◽  
Guang-Hua Cui ◽  
Jin Lin

In the title compound, [Er2(C4H4O4)3(H2O)2] n , the asymmetric unit consists of two ErIII cations, three succinate anions and two coordinated water molecules. Both ErIII ions are in a tricapped trigonal–prismatic coordination environment. The Er atoms are bridged into a three-dimensional framework by succinate anions, which exhibit anti and gauche conformations with different coordination modes. The crystal structure is stabilized by O—H...O hydrogen bonds [O...O = 2.715 (8)–2.936 (8) Å].


2014 ◽  
Vol 12 (2) ◽  
pp. 220-226 ◽  
Author(s):  
Nuša Hojnik ◽  
Matjaž Kristl ◽  
Amalija Golobič ◽  
Zvonko Jagličić ◽  
Miha Drofenik

AbstractThis article reports the synthesis of novel, rare-earth coordination complexes with nicotinic acid. Three compounds with the general formula Ln2[(C5H4NCOO)6(H2O)4] (Ln = Yb, 1; Ln = Gd, 2; Ln = Nd, 3) were prepared from relatively cheap and readily available reactants. Their compositions and structure were characterized by IR spectroscopy and single-crystal X-ray diffraction. The magnetic and thermogravimetric properties were also studied. The complexes consist of centrosymetric, dimeric molecules having all six nicotinato ligands coordinated with the central atom in the bidentate mode. The coordination environment of the Ln3+ for all three compounds is 8. Here we describe the crystal structure of Yb and Gd complexes with nicotinic acid.


2019 ◽  
Vol 74 (6) ◽  
pp. 513-518
Author(s):  
Matthias Folchnandt ◽  
Daniel Rudolph ◽  
Jean-Louis Hoslauer ◽  
Thomas Schleid

AbstractThe synthesis and crystal structure of a series of rare earth metal hydride tellurides with the composition REHTe (RE = Y, La–Nd, Gd–Er) is reported. These compounds have been obtained by the reaction of rare earth metal dihydrides (REH2) with elemental tellurium in sealed tantalum capsules at T = 700°C using cesium chloride (CsCl) as fluxing agent, which can be washed away with water due to the astonishing insensitivity of these hydride tellurides (REHTe) against hydrolysis. All of the compounds crystallize in the hexagonal space group P6̅m2 with a filled WC-type crystal structure, exhibiting a mutual trigonal-prismatic coordination of the heavy ions (RE3+ and Te2−), while the hydride anions reside in the trigonal prismatic voids surrounded by three rare earth metal cations expanding their coordination pattern to a tricapped trigonal prism. This 1H-type crystal structure is compared with the 1H- and 2H-type structures of the respective hydride selenides (REHSe, RE = Y, La–Nd, Gd–Tm, Lu). Both hexagonal basic crystal structures can be derived from the AlB2-type structure as demonstrated in a Bärnighausen tree by group-subgroup relationships.


Author(s):  
Rongqing Shang ◽  
An T. Nguyen ◽  
Allan He ◽  
Susan M. Kauzlarich

A rare-earth-containing compound, ytterbium aluminium antimonide, Yb3AlSb3 (Ca3AlAs3-type structure), has been successfully synthesized within the Yb–Al–Sb system through flux methods. According to the Zintl formalism, this structure is nominally made up of (Yb2+)3[(Al1−)(1b – Sb2−)2(2b – Sb1−)], where 1b and 2b indicate 1-bonded and 2-bonded, respectively, and Al is treated as part of the covalent anionic network. The crystal structure features infinite corner-sharing AlSb4 tetrahedra, [AlSb2Sb2/2]6−, with Yb2+ cations residing between the tetrahedra to provide charge balance. Herein, the synthetic conditions, the crystal structure determined from single-crystal X-ray diffraction data, and electronic structure calculations are reported.


2016 ◽  
Vol 72 (12) ◽  
pp. 1683-1686 ◽  
Author(s):  
Iuliia Shatrava ◽  
Kateryna Gubina ◽  
Vladimir Ovchynnikov ◽  
Viktoriya Dyakonenko ◽  
Vladimir Amirkhanov

In the molecular structure of the title compound, [CaNa(C10H20Cl3N3O2P)3(H2O)], the Ca2+ion has a slightly distorted octahedral coordination environment defined by six O atoms which belong to the carbonyl and phosphoryl groups of the three coordinating ligands. Two Cl atoms of CCl3groups and four O atoms form the coordination environment of the Na+ion: three from the carbonyl groups of ligands and one O atom from a coordinating water molecule. In the crystal, the bimetallic complexes are assembled into chains along thec-axis directionviaO—H...O hydrogen bonds that involve the coordinating water molecules and the phosphoryl groups.


2017 ◽  
Vol 73 (9) ◽  
pp. 1302-1304 ◽  
Author(s):  
Hicham El Hamdani ◽  
Mohammed El Amane ◽  
Carine Duhayon

The title complex, [Co(C7H7N4O2)2(H2O)4], comprises mononuclear molecules consisting of a CoIIion, two deprotonated theophylline ligands (systematic name: 1,3-dimethyl-7H-purine-2,6-dione) and four coordinating water molecules. The CoIIatom lies on an inversion centre and has a slightly distorted octahedral coordination environment, with two N atoms of twotrans-oriented theophylline ligands and the O atoms of four water molecules. An intramolecular hydrogen bond stabilizes this conformation. A three-dimensional supramolecular network structure is formed by intermolecular O—H...O and O—H...N hydrogen bonds.


2013 ◽  
Vol 69 (12) ◽  
pp. 1503-1508 ◽  
Author(s):  
Thazhe Kootteri Prasad ◽  
M. V. Rajasekharan

Three three-dimensional coordination polymers,viz.poly[[diaqua-μ4-oxydiacetato-di-μ4-sulfato-dipraseodymium(III)] hemihydrate], [Pr2(C4H4O5)(SO4)2(H2O)2]·0.5H2O, (I), poly[[diaquadi-μ3-oxydiacetato-μ3-sulfato-dineodymium(III)] 1.32-hydrate], [Nd2(C4H4O5)2(SO4)(H2O)2]·1.32H2O, (II), and poly[[diaquadi-μ3-oxydiacetato-μ3-sulfato-disamarium(III)] 1.32-hydrate], [Sm2(C4H4O5)2(SO4)(H2O)2]·1.32H2O, (III), were obtained by hydrothermal reactions of the respective lanthanide oxides and ZnSO4with oxydiacetic acid (odaH2). The Nd3+and Sm3+compounds form isomorphous crystal structures in which the lanthanide cations are nine-coordinate, having a tricapped trigonal prismatic coordination. The Pr3+compound has an entirely different crystal structure in which two types of coordination polyhedra are observed,viz.nine-coordinate (trigonal prism) and ten-coordinate (bicapped square antiprism). The sulfate anions show various coordination modes, one of which has only rarely been observed crystallographically to date.


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