Two-step photoionization of Na2: dependence on alignment

Laser light is used for two-step photoionization of Na₂. the first step depends on the moleculer orientation, the second step doesnot. This yields a method for the analysis of molecular alignment.     

Zur Kenntnis des Natrium-tetrahydroxoaluminat-chlorids Na2[Al(OH)4]Cl

On the Sodium Tetrahydroxoaluminate Chloride Na₂[Al(OH)₄]Cl The hitherto unknown compound Na₂[Al(OH)₄]Cl was prepared by crystallisation from a NaCl containing sodium aluminate solution. According to the X-ray single crystal investigation (tetragonal, space group P4/nmm, a = 7.541 Å, c = 5.059 Å, Z = 2) the compound represents the first example of a crystalline hydroxoaluminate with monomeric [Al(OH)₄]^? anions. Cl^? shows a quadratic anti prismatic coordination to 4 Na⁺ and over hydrogen bonds to 4 O^2? while Na⁺ is octahedrally coordinated by 4 O^2? and 2 Cl^? (axial). The results of the crystal structure analysis are confirmed by ²⁷Al and ²³Na MAS NMR investigations. Na₂[Al(OH)₄]Cl decomposes at about 200°C without intermediates under formation of β-NaAlO₂ and NaCl.     

Linear synthesis of the tumor-associated carbohydrate antigens Globo-H,SSEA-3, and Gb3

The tumor-associated carbohydrate antigens Globo-H, SSEA-3, and Gb3 were synthesized in a linear fashion using glycosyl phosphate monosaccharide building blocks. All of the building blocks were prepared from readily available common precursors. The difficult alpha-(1-->4-cis)-galactosidic linkage was installed using a galactosyl phosphate donor with high selectivity. Introduction of the beta-galactosamine unit required the screening a variety of amine protecting groups to ensure good donor reactivity and protecting group compatibility. An N-trichloroacetyl-protected galactosamine donor performed best for the installation of the beta-glycosidic linkage. Conversion of the trichloroacetyl group to the N-acetyl group was achieved under mild conditions, fully compatible with the presence of multiple glycosidic bonds. This synthetic strategy is expected to be amenable to the synthesis of the globo-series of tumor antigens on solid-support.     

Crystal and molecular structure of 6,13-Di(ethoxycarbonyl)-7,12-dimethyl-dibenzo [b.i.]-1,4,8,11-tetraaza[14]annulenato(2-) nitrosocobaltat [C26H26O5N5Co] and the neutral ligand [C26H28O4N4]

Both title compounds crystallize in the orthorhombic space group Pnma with 4 formular units in the unit cell. The lattice parameters are: [C₂₆H₂₆O₅N₅Co], a = 8.589(4), b = 19.395(3), and c = 14.850(3) Å;[C₂₆H₂₈O₄N₄], a = 8.413(7), b = 19.166(4), and c = 14.807(28) Å. The crystal structures have been determined by direct methods and refined by full-matrix least square calculations. The ligands have a pronounced saddle-shaped conformation in each structure because of interactions of the methyl groups with the benzene rings. The overall conformations of the neutral ligand and the cobalt complex are remarkably similar.     

Crystal and molecular structure of 3β-hydroxy-5β-estr-8(14)-en-17-one

The title compound crystallizes in the orthorhombic space group P2₁2₁2₁ with 4 formula units C₁₈H₂₆O₂ in the unit cell. The lattice constants are a = 10.356(2) Å, b = 19.743(3) Å, and c = 7.487(1) Å. The structure was solved by direct methods of phases determination and refined by least-squares calculations to the conventional R = 0.054. The configuration and conformation of the molecule were determined and compared with those of Δ-8,14-anhydrodigitoxigenin.     

Crystal and Molecular Structures of Modified Progestagens (IV). 17α-Azidomethyl-17β-hydroxy-estra-4,9-dien-3-one,C19H25N3O2

The crystal and molecular structure of 17α-azidomethyl-17β-hydroxy-estra-4,9-dien-3-one has been determined by X-ray structure analysis. It crystallizes in the orthorhombie space group P 2₁2₁2₁ with cell parameters a = 9.118(1), b = 9.252(1), and c = 20.444(2) Å. The structure was solved by MULTAN-82 and refined to R = 0.042 for 1408 observed reflections. Steroid ring and 17β-side chain conformations are discussed in the paper. Intermolecular hydrogen bridges between hydroxyl groups and carbonyl oxygen atoms link molecules forming chains in c-direction.     

Crystal and Molecular Structure of 3-Methoxy-estra-1,3,5(10)-trien-17β-ol

The crystal structure determination of the title compound was undertaken to determine the conformational flexibility of the steroid skeleton. 3-Methoxy-estra-1,3,5(10)-trien-17β-ol (C₁₉H₂₆O₂) crystallizes in the space group P2₁2₁2₁ with Z = 12, a = 12.589(2), b = 16.274(5), and c = 23.535(6) Å. The structure was solved by direct methods and refined to R = 0.056. Three symmetry independent molecules having different molecular conformations were observed in the crystal. The most flexible region of the molecules is the B ring which adopts following conformations: 7α,8β-half-chair, 8β-sofa, and an intermediate form between half-chair and sofa.     

Crystal and molecular structure of 3-methoxy-estra-1,3,5(10)-triene-14β,17β-diol,C19H26O3

The crystal and molecular structure of 3-methoxy-estra-1,3,5(10)-triene-14β,17β-diol has been determined by single crystal X-ray analysis. It crystallizes in the orthorhombic space group P2₁2₁2₁ with cell parameters a = 8.965(2), b = 30.520(7), and c = 6.031(2) A. The structure was solved by the POSIT system and refined by least-squares calculations to the conventional R factor of 0.075. The steroid rings A, B, and C have planar, 7α, 8β-half chair, and chair conformations, respectively. The ring D is intermediate between 13α, 14β-half chair and 13α-envelope. Rings B and C are trans-fused, and rings C and D are cis-fused. There are intra- as well as intermolecular hydrogen bonds between both hydroxyl groups of the steroid molecule.