Pr4(SeO3)2(SeO4)F6 und NaSm(SeO3)(SeO4): Selenit‐Selenate der Selten‐Erd‐Elemente |
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Authors: | Ina Krü germann,Mathias S. Wickleder |
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Abstract: | Pr4(SeO3)2(SeO4)F6 and NaSm(SeO3)(SeO4): Selenite‐Selenates of Rare Earth Elements Light green single crystals of Pr4(SeO3)2(SeO4)F6 have been obtained from the decomposition of Pr2(SeO4)3 in the presence of LiF in a gold ampoule. The monoclinic compound (C2/c, Z = 4, a = 2230.5(3), b = 710.54(9), c = 835.6(1) pm, β = 98.05(2)°, Rall = 0.0341) contains two crystallographically different Pr3+ ions. Pr(1)3+ is attached by six fluoride ions and two chelating SeO32– groups (CN = 10), Pr(2)3+ is surrounded by four fluoride ions, three monodentate SeO32– and two SeO42– groups. One of the latter acts as a chelating ligand, so the CN of Pr(2)3+ is 10. The selenite ions are themselves coordinated by five and the selenate ions by four Pr3+ ions. The coordination number of the F– ions is three and four, respectively. The linkage of the coordination polyhedra leads to cavities in the crystal structure which incorporate the lone pairs of the selenite ions. The reaction of Sm2(SeO4)3 and NaCl in gold ampoules yielded light yellow single crystals of NaSm(SeO3)(SeO4). The monoclinic compound (P21/c, Z = 4, a = 1066.9(2), b = 691.66(8), c = 825.88(9) pm, β = 91.00(2)°, Rall = 0.0530) contains tenfold oxygen coordinated Sm3+ ions. The oxygen atoms belong to five SeO32– and two SeO42– ions. Two of the SeO32– groups as well as one of the SeO42– groups act as a chelating ligand. The sodium ions are surrounded by five SeO42– ions and one SeO32– group. One of the selenate ions is attached chelating leading to a coordination number of seven. Each selenite group is coordinated by six (5 × Sm3+ and 1 × Na+), each selenate ion by seven cations (5 × Na+ and 2 × Sm3+). |
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Keywords: | Lanthanides Crystal structure Selenites, Selenates Lone pair effect |
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