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Cs[Tf2N]: a second polymorph with a layered structure.

ABSTRACT: The structural determination of the ionic liquid, caesium bis-[(tri-fluoro-meth-yl)sulfon-yl]imide or poly[[μ4-bis-[(tri-fluoro-meth-yl)sulfon-yl]imido]caesium(I)], Cs[N(SO2CF3)2] or Cs[Tf2N], reveals a second polymorph that also crystallizes in a layer structure possessing monoclinic P21/c symmetry at 120 K instead of C2/c for the known polymorph [Xue et al. (2002 ▸). Solid State Sci.4, 1535-1545]. The caesium ions in the cationic layers are coordinated by the sulfonyl groups of the bis-triflimide mol-ecules from anion layers while the tri-fluoro-methyl groups are oriented in the opposite direction, forming a non-polar surface separating the layers. The layer direction is (100).

SUBMITTER: Stritzinger JT

PROVIDER: S-EPMC5946987 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Crystal structures of Zn(cyclam)I2 (second monoclinic polymorph) and Zn(cyclam)I(I3).

Project description:The asymmetric unit of the first title compound iodido-(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ4 N 1,N 4,N 8,N 11)zinc(II) iodide, [ZnI(C10H24N4)]I, I, consists of the zinc-cyclam macrocyclic cation with one iodide anion coordinated to the metal ion [Zn-I = 2.6619 (5) Å] and the second present as a counter-ion. The asymmetric unit of the second title compound iodido-(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ4 N 1,N 4,N 8,N 11)zinc(II) triiodide, [ZnI(C10H24N4)]I3, II, consists of half of the centrosymmetric macrocyclic cation, in which the ZnII ion coordinated to an iodide anion [Zn-I = 2.766 (2) Å] is disordered over two positions [Zn⋯Zn = 0.810 (3) Å], and of the two halves of the crystallographically non-equivalent, non-coordinated, centrosymmetric triiodide anions. In both compounds, the N,N,N,N-tetra-dentate macrocyclic ligand is present in the most energetically favored trans-III conformation. In the crystals of I, the [Zn(C10H24N4)I]+ cations and the non-coordinated iodide anions are linked by N-H⋯I and bifurcated N-H⋯(I,I) hydrogen bonds, resulting in the formation of two-dimensional networks lying parallel to the (001) and (101) planes. In contrast, the crystals of II are built up from infinite chains of the five-coordinate macrocyclic units arranged along the b-axis direction and perpendicular sheets formed of the triiodide counter-ions without significant hydrogen bonding between them.

| S-EPMC8587993 | biostudies-literature

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| S-EPMC8597838 | biostudies-literature

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Project description:Diosgenone [(20S,22R,25R)-spirost-4-en-3-one, C(27)H(40)O(3)] has been proposed as a new therapeutic alternative for the treatment of malaria. The first X-ray structure report for diosgenone was by Piro et al. [(2002). Z. Naturforsch. Teil C, 57, 947-950] in the space group P2(1) (Z' = 2). We now report a new polymorph in the same space group, with two mol-ecules in the asymmetric unit. Both mol-ecules have similar conformations, characterized by a skewed envelope A ring, which contains the C=C bond conjugated with the ketone functionality at C3. The dimorphism results from a modification of the relative orientation of the mol-ecules in the asymmetric unit: two independent mol-ecules were arranged anti-parallel in the Piro report, while they are parallel in the present determination.

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Project description:Bismuth-based halide perovskites are nontoxic alternatives to widely studied lead-based perovskites for optoelectronic applications. Here, we synthesized Cs2NaBiCl6 thin films and attempted to synthesize Cs2NaBiBr6 using physical vapor deposition. While Cs2NaBiCl6 forms a stable cubic structure with a 3.4 eV band gap and could be synthesized successfully, Cs2NaBiBr6 does not form and is unstable with respect to dissociation into Cs3-xNaxBi2Br9 and Cs3-xNaxBiBr6. Furthermore, the close X-ray diffraction patterns of Cs3-xNaxBi2Br9 and Cs2NaBiBr6 raise doubts about the previous reports of the latter's formation based on X-ray diffraction alone.

| S-EPMC11256743 | biostudies-literature

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