Cover Picture: Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides RE12Ge7−xSb21 (RE=La–Pr) (Chem. Asian J. 9/2009)

Abstract

Succeeding RE6Ge5−xSb11+x, the ternary rare-earth germanium antimonides RE12Ge7−xSb21 (RE=La–Pr; x=0.4–0.5) represent the next level in an emerging structural series based on assemblies of RE6 trigonal prisms delimited by a polyanionic network of Ge and Sb atoms. The new orthorhombic structure type displays a wealth of bonding motifs, including Ge2 pairs, GeSb3 trigonal planes, and hypervalently bonded GeSb kinked sheets. H. Bie and A. Mar attempt bonding analysis through a Zintl–Klemm approach, which suggests that full electron transfer from the RE atoms to the anionic substructure cannot be assumed. This is confirmed by band-structure calculations, which also reveal the importance of GeSb and SbSb bonding. For the details, turn to their Full Paper on page 1465 ff.