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Several alkaline earth or rare earth binary monosilicides and -germanides possess complex bonding properties, such as polycation formation exceeding the scope of classical electron counting rules. In this study, we present characterization by powder and single-crystal diffraction and thermal analysis of CeGe, one of the few monogermanides crystallizing in the FeB-type structure. Comparative computational investigations for structure types experimentally observed for monogermanides and alternative structures with different structural motifs were performed to gain energetical insights into this family of compounds, underlining the preference for infinite germanium chains over other structural motifs. Formation enthalpy calculations and structural chemical analysis highlight the special position of FeB-type compounds among the monogermanides. [ABSTRACT FROM AUTHOR]

Direct synthesis and structural characterization of a series of polar rare earth palladium germanides of RPdGe composition (R = La-Nd, Sm) is reported. The crystal structure of the Nd representative was determined by single-crystal X-ray diffraction analysis (UCoSi-type, SG: Ibam, oI40, Z = 4, a = 10.1410(6), b = 12.0542(8), c = 6.1318(4) Å, wR = 0.0306, 669 F values, 31 variables). The crystal structures of the other homologues were ensured by powder X-ray diffraction pattern analysis. A smooth variation of the cell dimensions is observed through the rare earth series. The structure of the studied compounds can be interpreted as consisting of a complex three-dimensional [PdGe] network spaced by the rare earth cations. Within the concept of symmetry reduction, a Bärnighausen tree is used to rationalize the related crystal structures of the RPdGe, RPdGe and RPdGe ternary compounds, enriching the large family of the BaAl derivatives. Moreover, syntheses with metal fluxes were performed, some of which were successful to obtain large crystals of LaPdGe (using Bi as solvent) and NdPdGe (using Pb as solvent) stoichiometry. [ABSTRACT FROM AUTHOR]