Cover illustration: The two types of ladder formed by ammonium carboxylate salts. Type II (left) has repeating R43(10) rings, whereas type III (right) has alternating R42(8) and R44(12) rings. The three hydrogen bonds from the -NH3+ cation consist of two legs and one rung. See Lemmerer [Acta Cryst. (2011), C67, o92-o99].
La4.27Mg2.89Zn30, an intermetallic compound, is a new structure type which crystallizes in the hexagonal space group P63/mmc. The structure is an intergrowth of fragments of the CaCu5 and Th2Ni17 types. Strong positional disorder is observed along the six- and threefold axes.
The novel structure of Na8Ca1.5Mg12.5(PO4)12 consists of MgOx (x = 5 and 6) polyhedra and MO7 (M = Mg or Na) octahedra linked directly through common corners or edges to form a rigid three-dimensional skeleton, reinforced by corner-sharing between identical Mg12MO48 units.
The copper–manganese phosphate solid solution Cu0.5Mn2.5(PO4)2 was prepared by a reaction between its constituent oxides at 1223 K under argon. The compound has a graftonite-type structure, viz. (Mn,Fe,Ca,Mg)3(PO4)2, with CuII located in one of three distinct metal cation sites.