Cover illustration: A Topologically Novel Binuclear Silver Complex of Di-2-pyridyl Sulfide,
see Anderson and Steel, pages 223-225. Displacement ellipsoids are shown at the 70% probability level for non-H atoms and
H atoms are represented as spheres of arbitrary radii.
2,3-Dihydro-8-hydroxy-5,7-dimethoxy-2-phenyl-4H-1-benzo-pyran-4-one was isolated from Uvaria dulcis Dunal. The determination of its crystal structure and that of its bromo derivative were carried out to confirm the structures proposed from spectroscopic data.
This compound shows no unusual intramolecular or intermolecular distances or angles. The dihydrothieno[2,3-b]pyridine moiety is planar and the angle between this plane and that of the 4-phenyl ring is 85.8(1)°. The molecules are linked to form chains via intermolecular N-H⋯O hydrogen bonds.
The coumarin moiety in this compound is planar and the tetrahydrobenzene ring adopts a half-chair conformation. The planes of the coumarin and phenyl rings form a dihedral angle of 50.97(8)°. The crystal structure is stabilized by O-H⋯O hydrogen bonds involving carbonyl and hydroxyl O atoms.
The tetrametaphosphimate rings in (NH4)4(PO2NH)4.4H2O exhibit a chair conformation and are linked by N-H⋯O hydrogen bonds to form columns along . These columns are interconnected by O-H⋯O and N-H⋯O hydrogen bonds through the water molecules and ammonium ions.
The structure of Na13K4Ga47.45 contains Ga12 icosahedra and oligomeric icosahedral units (Ga28 trimers) packed within a three-dimensional framework. The interpolyhedral voids are occupied by the alkali-metal cations.
The structure of dilithium vanadyl silicate is isotypic with that of Li2TiOSiO4. It is built up from VO5 square pyramids sharing corners with SiO4 tetrahedra to form layers between which the Li ions are situated.