Cover illustration: A view of the extended structure of 2,5-dioxopiperazine-1,4-diacetic acid, with hydrogen bonds shown as dashed lines. H atoms not participating in hydrogen bonding have been omitted for clarity. See Ramos Silva, Matos Beja, Paixão, Sobral, Cabral & Rocha Gonsalves [Acta Cryst. (2003), C59, o562-o563].
The structure of [Co(H2O)4][VO(PO4)]2 consists of vanadyl phosphate layers containing corner-sharing VO5 square pyramids and PO4 tetrahedra. These layers are linked by interlayer CoO6 octahedra into a three-dimensional structure.
The crystal structures of two novel phyllosilicates have been characterized by single-crystal X-ray diffraction. The caesium phyllosilicate has silica sheets composed of four- and six-membered rings whereas the rubidium compound is described by six-membered-ring sheets.
The structure of the new synthetic thortveitite-type compound diyttrium disilicate, β-Y2Si2O7, has been determined by single-crystal X-ray diffraction and refined in the C2/m space group at 100 and 280 K.