Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture (Angew. Chem. Int. Ed. 9/1998)
The cover picture shows the encapsulation of a bromide ion inside the novel hexanuclear nickel cage [Ni6(atu)8Br]3+ (Hatu = amidinothiourea); this representation was generated with the Persistence of Vision (POV) package, version 3.02 for windows (red: Br, green: Ni, yellow: S; blue: N, gray: C). A combination of Lewis acid - base and hydrogen-bonding interactions result in the assembly of square-planar (Ni[atu)2]2+ units into this superstructure. The formation of this cage is anion-dependent and has been shown to be templated by a halide (i.e., chloride or bromide) which, in the final structure, remains encapsulated at its center forming eight hydrogen bonds with NH groups from the ligands and two Lewis acid-base interactions with two NiII ions. Anion-supported self-assembly is currently an intensively investigated and fruitful area of research (see also the communication by Ward et al. on pages 1279–1281). More details concerning the Ni6 complex are reported by Mingos et a1 on pages 1258–1261.