Crystal structure of N'-[(1E)-1-(6-methyl-2,4-dioxo-3,4-di-hydro-2H-pyran-3-yl-idene)eth-yl]benzene-sulfono-hydrazide.

In the title compound, C14H14N2O5S, the mol-ecule exists in the enamine (C=C-NH) tautomeric form. The hydrazone fragment derived from the 3-acetyl-4-hy-droxy-6-methyl-2H-pyran-2-one moiety is approximately planar, with a maximum deviation of 0.1291 (11) Šfor the N atom bound to the S atom of the benzensulfono-hydrazide group. The latter adopts a gauche conformation relative to the hydrazone N-N bond, with an N-N-S angle of 113.54 (10)°. There is an intra-molecular N-H⋯O=C hydrogen bond that stabilizes the tautomeric form. In the crystal, mol-ecules are linked by N-H⋯O=C hydrogen bonds into chains extending parallel to [100].

N'-[(4Z)-1-(3-Methyl-5-oxo-1-phenyl-4,5-di-hydro-1H-pyrazol-4-yl-idene)hex-yl]benzene-sulfono-hydrazide.

In the title compound, C22H26N4O3S, the dihedral angle between the pyrazoloneand phenyl rings is 21.73 (4)°. The benzensulfono-hydrazide group adopts a gauche conformation about the N-N vector. The C-N-N-S torsion angle is -109.88 (13)°. The mol-ecule exists as the enamine tautomeric form (C=C-NH). An intra-molecular N-H⋯O=C hydrogen bond occurs. In the crystal, mol-ecules are linked by pairs of N-H⋯O=C hydrogen bonds, forming centrosymmetric dimers.

Isopolyoxometalates derived from arylstibonic acids with "reverse-Keggin ion" structures based on [M(RSb)12O28] cores, M = Co(II) or Zn(II).

The preparations and structures are described of four new polyoxostibonates, [Co(p-MeC(6)H(4)Sb)(12)O(28){Co(H(2)O)(3)}(4)]Cl(2)·6H(2)O, [Co(p-ClC(6)H(4)Sb)(12)O(28){Co(H(2)O)(3)}(4)]Cl(2)·22H(2)O, (PhCH(2)NMe(3))(2)[Zn(p-ClC(6)H(4)Sb)(12)O(28)Zn(4)Cl(2.54)Br(1.46)]·8MeCN·H(2)O and [BaCoH(4)(p-MeC(6)H(4)Sb)O(28)]·5H(2)O. Each of these has a framework of 12 (RSb) groups linked by 28 O atoms, with one transition metal ion in a tetrahedral site in the centre. Other metal ions are coordinated to the polyhedral faces. Three of the complexes have the ε Keggin ion geometry, while the fourth is a δ isomer.

(±)-1-{8'-(tert-Butyl-diphenyl-silyloxy-meth-yl)-1',7'-dioxaspiro-[5.5]undecan-2'-yl}uridine.

The crystal structure of the title compound, C(30)H(38)N(2)O(5)Si, has been investigated to establish the relative stereochemistry at the spiro ring junction and the two anomeric centres. Each of the O atoms in the tetra-hydro-pyran rings adopts an axial position on the neighbouring ring. This bis--diaxial conformation is adopted, thus gaining maximum stablization from the anomeric effect. The silyl-protected hydroxy-methyl and uracil substituents adopt equatorial positions on their associated tetra-hydro-pyran rings, thereby minimizing unfavourable steric inter-actions. The dimeric (2'R*,6'R*,8'R*)- and (2'S*,6'S*,8'S*)-uridine units are connected to each other across crystallographic inversion centres via inter-molecular N-H⋯O hydrogen bonds.