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- Title
On the dimorphism of Pr<sub>6</sub>Mo<sub>10</sub>O<sub>39</sub>.
- Authors
Rudolph, Daniel; Laufer, Sonja; Hartenbach, Ingo
- Abstract
Attempts to synthesize Pr4Mo7O27 using Pr, Pr6O11 and MoO3 in a molar ratio of 8:6:77 led to a main product of scheelite-type Pr0.667[MoO4] and few single crystals of the triclinic A-type Pr6Mo10O39. The latter crystallizes in space group P1¯ (a = 945.25(1), b = 1058.49(2), c = 1815.16(3) pm; α = 104.149(1), β = 95.220(1), γ = 102.617(1)°, Z = 2). Its crystal structure comprises six crystallographically independent Pr3+ cations, eight tetrahedral [MoO4]2- units, and one [Mo2O7]2- entity. The cations display coordination numbers of seven (1×) and eight (5×), while the [MoO4]2- tetrahedra are surrounded by five Pr3+ cations each. The [Mo2O7]2- anions exhibit a coordination environment of seven Pr3+ cations. The attempt to synthesize PrF[MoO4] using PrOF (from in situ thermal decomposition of PrF[CO3]) as reagent did not lead to the desired product but to monoclinic B-type Pr6Mo10O39. This slightly less dense modification compared to its triclinic analogue crystallizes in space group C2/c (a = 1247.93(3), b = 1989.68(6), c = 1392.52 (4) pm, β = 100.505(2)°, Z = 4) with three crystallographically independent Pr3+ cations, four [MoO4]2- tetrahedra, and again one [Mo2O7]2- unit in the crystal structure. Thus, both Pr6Mo10O39 modifications are better described with the structured formula Pr6[MoO4]8[Mo2O7]. The coordination numbers around the Pr3+ cations are seven (1×) and eight (2×) while all four [MoO4]2- anions are again surrounded by five Pr3+ cations each. Six of the latter represent the coordination environment around the [Mo2O7]2- entities. Besides the thorough comparison of the crystal structures single crystal Raman spectra were recorded for both Pr6Mo10O39 phases.
- Subjects
DIMORPHISM (Biology); CHEMICAL synthesis; SINGLE crystals; SPACE groups; CRYSTAL structure
- Publication
Zeitschrift für Naturforschung B: A Journal of Chemical Sciences, 2017, Vol 72, Issue 11, p765
- ISSN
0932-0776
- Publication type
Article
- DOI
10.1515/znb-2017-0055