Crystal structure of poly-p-xylylene. I. The α form

The molecular conformation and the crystal structure of α-form poly-p-xylylene has been determined by x-ray diffraction. The polymer has a monoclinic unit cell with a = 5.92, b = 10.64, c (fiber axis) = 6.55 Å, and β = 134.7°. Two chains pass through the unit cell, and the space groups is C2/m. The packing fraction is 0.705. One monomer unit makes up the fiber identity period and the internal rotation angles are 0° and 90° for the ? CH₂? CH₂? and ? CH₂? ?? bonds, respectively. All benzene rings are in parallel orientation, perpendicular to the ac plane.     

Synthesis and Crystal Structure of α‐ThTe3

The binary thorium tritelluride, α‐ThTe₃, was synthesized by solid‐state methods at 1223 K. From a single‐crystal X‐ray diffraction study the material crystallizes in the TiS₃ structure type with two formula units in space group C²_2h–P2₁/m of the monoclinic system in a cell with lattice constants a = 6.1730 (4) Å, b = 4.3625(3) Å, c = 10.4161(6) Å, and β = 97.756(3)° (at 100 K). The asymmetric unit of this compound comprises one Th atom and three Te atoms each with site symmetry m. Each Th atom is coordinated to eight Te atoms in a bicapped trigonal‐pyramidal arrangement. Th–Te distances range from 3.1708(4) Å to 3.2496(6) Å. The structure features a Te–Te interaction 2.7631(8) Å in length, which is typical for a Te–Te single bond. Thus α‐ThTe₃ may be charge balanced and formulated as Th⁴⁺Te^2–Te₂^2–.     

The Crystal and Molecular Structure of 3-Oxo-17β-acetoxy-Δ4-14α-methyl-8α, 9β, 10α, 13α-estrene

The crystal and molecular structure of 3-oxo-17β-acetoxy-Δ⁴-14α-methyl-8α, 9β, 10α, 13α-estrene, C₂₁H₃₀O₃, has been determined by X-ray diffraction analysis. The crystals belong to the orthorhombic space group P2₁2₁2₁, with the cell dimensions a = 12.093 Å, b = 19.667 Å, c = 7.746 Å; Z = 4. Intensity data were collected at room temperature with an automatic four-circle diffractometer. The structure was solved by direct methods and the parameters were refined by least-squares analysis. All the hydrogen atoms were included in the refinement. The final R value was 0.038 for 1413 observed reflections. The conformation of ring A is intermediate between a half-chair and a 1, 2-diplanar form. The hydrogens at C(9) and C(10) are anti, the B/C ring junction is trans, and rings B and C adopt chair conformations. Ring D is cis fused and is halfway between C₂ and C_s forms.     

Crystal and molecular structure of 3-hydroxy-5-phenylisoxazole (α form)

The crystal structure of the α form of 3-hydroxy-5-phenylisoxazole has been determined from three-dimensional X-ray data. The crystals are monoclinic, space group P2₁/n with four molecules in the unit cell. The cell dimensions are: a = 10.41(2); b = 3.89(1); c = 19.14(4) Å; β = 96.1° (3). The structure was refined by the block-diagonal least-squares method to a final R value of 0.080 for 1111 observed reflections. The molecular dimensions are in good overall agreement with those in β form, while the packing is markedly different. Conjugation and planarity in the molecule are discussed.     

A novel synthesis of α-hydroxy- and α,α′-dihydroxyketone from α-iodo and α,α′-diiodo ketone using photoirradiation

A novel reaction of α-iodo ketone (α-iodocycloalkanone, α-iodo-β-alkoxy ester, and α-iodoacyclicketone) with irradiation under a high-pressure mercury lamp gave the corresponding α-hydroxyketone in good yields. In the case of α,α′-diiodo ketone, α,α′-dihydroxyketone which little has been reported until now was obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxy- and α,α′-dihydroxyketone.