June 1998 issue
cif-access (inorganic compounds)
RbCe(SO4)2.H2O has a framework structure composed of discrete sulfate tetrahedra interlinked by nine-coordinate Ce polyhedra. The framework contains large channels in which the Rb atoms reside, in contrast to the layered structure exhibited by the analogous tetrahydrate.
cif-access (organic compounds)
The porphyrin molecule in this compound shows significant conformational distortion in the vicinity of the beta-nitro group. This is attributed to steric interaction between a meso-phenyl group and the beta-nitro group.
The phenyl rings in this compound form a dihedral angle of 46.8(1)° and they make dihedral angles of 79.6(1) and 67.7(1)° with the naphthalene ring. The hydroxy groups are involved in O-H⋯O intramolecular hydrogen bonds.
Very different hydrogen-bonded networks are found in the two forms. The monoclinic form (in which the cation is trans-trans) has open fused columns and a unit-cell volume 5% greater than the triclinic form (in which the cation is trans-gauche), where the network contains fused clusters.
The structure of Nd2(Se2O5)3.H2SeO3.2H2O is built up from polar layers formed by Nd2O16 bipolyhedra and diselenite groups. Water and selenious acid occur on only one side of each layer.
The different colours of turquoise Cs3NiCl5 and orange CsNiCl3 are caused by the tetrahedral coordination of nickel(II) in the former and the octahedral coordination of nickel(II) in the latter.
Rb4Ta2S11 and Cs4Ta2S11 are new members of the growing family of compounds which contain an M2Q11 unit as a main structural feature. They were prepared via the reactive flux method.