Acta Crystallographica Section E: Crystallographic Communications最新文献

X-ray analysis and structure determination of fluoro­lactonization products from the reaction of oleanolic acid with Selectfluor^TM are reported.

The X-ray crystal structure data of 12-α-fluoro-3β-hy­droxy­olean-28,13β-olide methanol hemisolvate, 2C₃₀H₄₇FO₃·CH₃OH, (1), and 12-α-fluoro-3β-hy­droxy­taraxer-28,14β-olide methanol hemisolvate, 2C₃₀H₄₇FO₃·CH₃OH, (2), are described. The fluoro­lactonization of oleanolic acid using Selectfluor^TM yielded a mixture of the six-membered δ-lactone (1) and the unusual seven-membered γ-lactone (2) following a 1,2-shift of methyl C-27 from C-14 to C-13.

The structures of the four thio­glycosides, all Z-configured across the C=N(CN) moiety, differ in many important torsion angles. The C—N bond lengths at the central carbon atom of the carbamimido­thio­ate group are almost equal. Three of the four structures form layers by hydrogen bonding.

The compounds 2′,3′,4′,6′-tetra-O-acetyl-β-d-gluco­pyranosyl N′-cyano-N-phenyl­carbamimido­thio­ate (C₂₂H₂₅N₃O₉S, 5a), 2′,3′,4′,6′-tetra-O-acetyl-β-d-galacto­pyranosyl N′-cyano-N-phenyl­carbamimido­thio­ate, (C₂₂H₂₅N₃O₉S, 5b), 2′,3′,4′,6′-tetra-O-acetyl-β-d-galacto­pyranosyl N′-cyano-N-methyl­carbamimido­thio­ate (C₁₇H₂₃N₃O₉S, 5c), and 2′,3′,4′,6′-tetra-O-acetyl-β-d-galacto­pyranosyl N′-cyano-N-p-tolyl­carbamimido­thio­ate (C₂₃H₂₇N₃O₉S, 5d) all crystallize in P2₁2₁2₁ with Z = 4. For all four structures, the configuration across the central (formal) C=N(CN) double bond of the carbamimido­thio­ate group is Z. The torsion angles C5—O1—C1—S (standard sugar numbering) are all close to 180°, confirming the β position of the substituent. Compound 5b involves an intra­molecular hydrogen bond N—H⋯O1; in 5c this contact is the weaker branch of a three-centre inter­action, whereas in 5a and 5d the H⋯O distances are much longer and do not represent significant inter­actions. The C—N bond lengths at the central carbon atom of the carbamimido­thio­ate group are almost equal. All C—O—C=O torsion angles of the acetyl groups correspond to a synperiplanar geometry, but otherwise all four mol­ecules display a high degree of conformational flexibility, with many widely differing torsion angles for equivalent groups. In the crystal packing, 5a, 5c and 5d form layer structures involving the classical hydrogen bond N—H⋯N_cyano and a variety of ‘weak’ hydrogen bonds C—H⋯O or C—H⋯S. The packing of 5b is almost featureless and involves a large number of borderline ‘weak’ hydrogen bonds. In an appendix, a potted history of wavelength preferences for structure determination is presented and it is recommended that, even for small organic crystals in non-centrosymmetric space groups, the use of Mo radiation should be considered.

In the title mol­ecule, C₁₁H₁₁BrO₃, the di­hydro­indene moiety is essentially planar but with a slight twist in the saturated portion of the five-membered ring. The meth­oxy groups lie close to the above plane. In the crystal, π-stacking inter­actions between six-membered rings form stacks of mol­ecules extending along the a-axis directions, which are linked by weak C—H⋯O and C—H⋯Br hydrogen bonds.

In the title mol­ecule, C₁₁H₁₁BrO₃, the di­hydro­indene moiety is essentially planar but with a slight twist in the saturated portion of the five-membered ring. The meth­oxy groups lie close to the above plane. In the crystal, π-stacking inter­actions between six-membered rings form stacks of mol­ecules extending along the a-axis direction, which are linked by weak C—H⋯O and C—H⋯Br hydrogen bonds. A Hirshfeld surface analysis was performed showing H⋯H, O⋯H/H⋯O and Br⋯H/H⋯Br contacts make the largest contributions to inter­molecular inter­actions in the crystal.

In [UO₂L(CH₃OH)]_n, the acetate group of the 1,2,4-triazol-based ligand bridges two uranyl cations, forming a neutral zigzag chain. A solid-state LMCT transition at 463 nm is responsible for the light-red colour of the compound.

In the title complex, [U(C₁₀H₇N₃O₃)O₂(CH₃OH)]_n, the U^VI cation has a typical penta­gonal–bipyramidal environment with the equatorial plane defined by one N and two O atoms of one doubly deprotonated 2-[5-(2-hy­droxy­phen­yl)-1H-1,2,4-triazol-3-yl]acetic acid ligand, a carboxyl­ate O atom of the symmetry-related ligand and the O atom of the methanol mol­ecule [U—N/O_eq 2.256 (4)–2.504 (5) Å]. The axial positions are occupied by two oxide O atoms. The equatorial atoms are almost coplanar, with the largest deviation from the mean plane being 0.121 Å for one of the O atoms. The benzene and triazole rings of the tetra­dentate chelating–bridging ligand are twisted by approximately 21.6 (2)° with respect to each other. The carboxyl­ate group of the ligand bridges two uranyl cations, forming a neutral zigzag chain reinforced by a strong O—H⋯O hydrogen bond. In the crystal, adjacent chains are linked into two-dimensional sheets parallel to the ac plane by C/N—H⋯N/O hydrogen bonding and π–π inter­actions. Further weak C—H⋯O contacts consolidate the three-dimensional supra­molecular architecture. In the solid state, the compound shows a broad medium intensity LMCT transition centred around 463 nm, which is responsible for its red colour.

Redetermination of the crystal structure of BiF₅ was undertaken to a much higher precision and quantum chemical calculations for an assignment of the Raman and IR bands.

The crystal structure of bis­muth penta­fluoride, BiF₅, was rerefined from single-crystal data. BiF₅ crystallizes in the α-UF₅ structure type in the form of colorless needles. In comparison with the previously reported crystal-structure model [Hebecker (1971#). Z. Anorg. Allg. Chem.384, 111–114], the lattice parameters and fractional atomic coordinates were determined to much higher precision and all atoms were refined anisotropically, leading to a significantly improved structure model. The Bi atom (site symmetry 4/m..) is surrounded by six F atoms in a distorted octa­hedral coordination environment. The [BiF₆] octa­hedra are corner-linked to form infinite straight chains extending parallel to [001]. Density functional theory (DFT) calculations at the PBE0/TZVP level of theory were performed on the crystal structure of BiF₅ to calculate its IR and Raman spectra. These are compared with experimental data.

The complex 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)meth­yl]pyridin-1-ium hexa­kis­(nitrato-O,O′)thorate was synthesized from layered solutions of Th(NO₃)₄·5H₂O and 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)meth­yl]pyridine (L).

Reaction of thorium(IV) nitrate with 2-[(4-phenyl-1H-1,2,3-triazol-1-yl)meth­yl]pyridine (L) yielded (LH)₂[Th(NO₃)₆] or (C₁₄H₁₃N₄)₂[Th(NO₃)₆] (1), instead of the expected mixed-ligand complex [Th(NO₃)₄L₂], which was detected in the mass spectrum of 1. In the structure, the [Th(NO₃)₆]²⁻ anions display an icosa­hedral coordination geometry and are connected by LH⁺ cations through C—H⋯O hydrogen bonds. The LH⁺ cations inter­act via N—H⋯N hydrogen bonds. Hirshfeld surface analysis indicates that the most important inter­actions are O⋯H/H⋯O hydrogen-bonding inter­actions, which represent a 55.2% contribution.

The Mo—Mo bond in the dinuclear mol­ecular title compound is 3.2323 (3) Å, in good agreement with related dinuclear molybdenum(I) compounds with cyclo­penta­dienyl (Cp) ligands.

The dinuclear mol­ecule of the title compound, [Mo₂(C₉H₁₃)₂(CO)₆] or [Mo(^tBuCp)(CO)₃]₂ where ^tBu and Cp are tert-butyl and cyclo­penta­dienyl, is centrosymmetric and is characterized by an Mo—Mo bond length of 3.2323 (3) Å. Imposed by inversion symmetry, the ^tBuCp and the carbonyl ligands are in a transoid arrangement to each other. In the crystal, inter­molecular C—H⋯O contacts lead to the formation of layers parallel to the bc plane.

Mol­ecules of the aryl diester, 2-methyl-1,4-phenyl­ene bis­(3,5-di­bromo­benzoate), crystallized out from the melt (m.p. = 502 K/DSC). The crystal structure consists of a C—H⋯Br hydrogen-bonded network and weaker, offset π–π inter­actions.

The aryl diester compound, 2-methyl-1,4-phenyl­ene bis­(3,5-di­bromo­benzoate), C₂₁H₁₂Br₄O₄, was synthesized by esterification of methyl hydro­quinone with 3,5-di­bromo­benzoic acid. A crystalline sample was obtained by cooling a sample of the melt (m.p. = 502 K/DSC) to room temperature. The mol­ecular structure consists of a central benzene ring with anti-3,5-di­bromo­benzoate groups symmetrically attached at the 1 and 4 positions and a methyl group attached at the 2 position of the central ring. In the crystal structure (space group P

The title mol­ecule is centrosymmetric, with a pyrazine ligand bridging two {Cu₁₀Ir₃} cluster units that are arranged in an unusual shape containing 13 vertices, 22 faces, and 32 sides.

Single crystals of the mol­ecular compound, {Cu₂₀Ir₆Cl₈(C₂₁H₂₄N₂)₆(C₄H₄N₂)₃]·3.18CH₃OH or [({Cu₁₀Ir₃}Cl₄(IMes)₃(pyrazine))₂(pyrazine)]·3.18CH₃OH [where IMes is 1,3-bis­(2,4,6-trimethylphen­yl)imidazol-2-yl­idene], with a unique heterometallic cluster have been prepared and the structure revealed using single-crystal X-ray diffraction. The mol­ecule is centrosymmetric with two {Cu₁₀Ir₃} cores bridged by a pyrazine ligand. The polymetallic cluster contains three stabilizing N-heterocyclic carbenes, four Cl ligands, and a non-bridging pyrazine ligand. Notably, the Cu—Ir core is arranged in an unusual shape containing 13 vertices, 22 faces, and 32 sides. The atoms within the trideca­metallic cluster are arranged in four planes, with 2, 4, 4, 3 metals in each plane. Ir atoms are present in alternate planes with an Ir atom featuring in the peripheral bimetallic plane, and two Ir atoms featuring on opposite sides of the non-adjacent tetra­metallic plane. The crystal contains two disordered methanol solvent mol­ecules with an additional region of non-modelled electron density corrected for using the SQUEEZE routine in PLATON [Spek (2015#). Acta Cryst. C71, 9–18]. The given chemical formula and other crystal data do not take into account the unmodelled methanol solvent mol­ecule(s).

Two inter­mediates, 4-amino-3,5-di­fluoro­benzo­nitrile, C₇H₄F₂N₂ (I), and ethyl 4-amino-3,5-di­fluoro­benzoate, C₉H₉F₂NO₂ (II), along with a visible-light-responsive azo­benzene derivative, diethyl 4,4′-(diazene-1,2-di­yl)bis­(3,5-di­fluoro­benzoate), C₁₈H₁₄F₄N₂O₄ (III), obtained by four-step synthetic procedure, were studied using single-crystal X-ray diffraction. In the crystals of I and II, the mol­ecules are connected by N—H⋯N, N—H⋯F and N—H⋯O hydrogen bonds, C—H⋯F short contacts, and π-stacking inter­actions. In the crystal of III, only stacking inter­actions between the mol­ecules are found.

The crystal structures of two inter­mediates, 4-amino-3,5-di­fluoro­benzo­nitrile, C₇H₄F₂N₂ (I), and ethyl 4-amino-3,5-di­fluoro­benzoate, C₉H₉F₂NO₂ (II), along with a visible-light-responsive azo­benzene derivative, diethyl 4,4′-(diazene-1,2-di­yl)bis­(3,5-di­fluoro­benzoate), C₁₈H₁₄F₄N₂O₄ (III), obtained by four-step synthetic procedure, were studied using single-crystal X-ray diffraction. The mol­ecules of I and II demonstrate the quinoid character of phenyl rings accompanied by the distortion of bond angles related to the presence of fluorine substituents in the 3 and 5 (ortho) positions. In the crystals of I and II, the mol­ecules are connected by N—H⋯N, N—H⋯F and N—H⋯O hydrogen bonds, C—H⋯F short contacts, and π-stacking inter­actions. In crystal of III, only stacking inter­actions between the mol­ecules are found.