Lanthanoid(III) oxide chloride oxoselenates(IV): A fascinating class of multinary compounds
| Autor: | Joseph Wontcheu, Thomas Schleid |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Lanthanide
Electron pair Stereochemistry Chemistry Mechanical Engineering Metals and Alloys chemistry.chemical_element Space group General Medicine Crystal structure Triclinic crystal system Oxygen Chloride Tetragonal crystal system Crystallography Mechanics of Materials Materials Chemistry medicine Orthorhombic crystal system Monoclinic crystal system medicine.drug |
| Zdroj: | Journal of Alloys and Compounds. 418:45-52 |
| ISSN: | 0925-8388 |
| DOI: | 10.1016/j.jallcom.2005.08.098 |
| Popis: | Compounds in the systems M 3+ -O 2- -Cl - -Se 4+ are more than just quaternaries, for they can offer both oxygen that is bonded to sele-nium(IV) to form discrete [SeO 3 ] 2- ψ 1 -tetrahedra ([SeO 3 E] 2- with E: non-bonding electron pair as pseudo-ligand) and oxygen that is only bonded to the trivalent lanthanoid (M = Ce-Lu) to form regular [OM 4 ] 10+ tetrahedra. The latter share edges and vertices in most cases to build up cationic chains ([OM 2 ] 4+ in Cl - -free Tb 2 O[SeO 3 ] 2 : a = 1064.57(7) pm, c= 521.56(4) pm, Z=4, tetragonal, P4 2 /ncm), double strands ([O 2 M 3 ] 5+ in Tb 3 O 2 Cl[SeO 3 ] 2 : a=535.16(4)pm, b= 1530.51(9) pm, c= 1081.72(7)pm, Z=4, orthorhombic, Pnma; Er 3 O 2 Cl[SeO 3 ] 2 : a = 1498.23(9) pm, b=1102.04(7) pm, c=547.95(4)pm, β=105.515(6)°, Z=4, monoclinic, C2/c) or layers ([O 3 M 4 ] 6 + in Yb 4 O 3 Cl 2 [SeO 3 ] 2 : a=853.87(6)pm, b=1145.92(8)pm, c=1195.46(8) pm, α=68.132(6)°, β=78.113(6)°, y=85.748(6)°, Z=2, triclinic, P1, [O 4 M 5 ] 7+ in Tb 5 O 4 Cb[SeO 3 ] 2 : a = 1229.13(8) pm, b = 546.17(4) pm, c = 978.79(6) pm, β=90.485(6)°, Z= 2, monoclinic, C2/m; [O 8 M 9 ] 11+ in Gd 9 O 9 Cl 3 [SeO 3 ] 4 : a = 680.17(5) pm, b=882.86(7)pm, c=960.18(7)pm, α=97.241(6)°, β=95.539(6)°, y=96.265(6)°, Z=1, triclinic, P1; [O 3 M 3 ] 3+ in CsEu 4 O 3 Cl 3 [SeO 3 ] 2 : a=545.09(4)pm, b=879.98(7)pm, c= 1597.45(9) pm, a=81.036(6)°, β=89.992(6)°, y= 71.925(6)°, Z=2, triclinic, P1). On the other hand and much like in the pure lanthanoid(III) oxoselenates(IV) M 2 [SeO 3 ] 3 themselves, segregation of the stereochemically active non-bonding electron pairs (one per Se 4+ cation) of the pyramidal [SeO 3 ] 2- units occurs, such that "lone-pair" channel or layer structures emerge. Sometimes even the "lone-pair" electrons of the chloride anions help to construct these structural features as also observed in the O 2- -free chloride oxoselenates(IV) MCl[SeO 3 ]. |
| Databáze: | OpenAIRE |
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