Synthesis, Crystal and Electronic Structures of the Pnictides AE3TrPn3 (AE = Sr, Ba; Tr = Al, Ga; Pn = P, As)

Crystals

Stanislav S. Stoyko²  Leonard H. Voss²  Hua He²  Svilen Bobev¹ 

[1] Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA;

关键词: arsenide;    barium;    crystal structure;    phosphide;    strontium;    Zintl phases;   

DOI  :  10.3390/cryst5040433

来源: mdpi

【 摘 要 】

The new ternary arsenides AE₃TrAs₃ (AE = Sr, Ba; Tr = Al, Ga) and their phosphide analogs Sr₃GaP₃ and Ba₃AlP₃ have been prepared by reactions of the respective elements at high temperatures. Single-crystal X-ray diffraction studies reveal that Sr₃AlAs₃ and Ba₃AlAs₃ adopt the Ba₃AlSb₃-type structure (Pearson symbol oC56, space group Cmce, Z = 8). This structure is also realized for Sr₃GaP₃ and Ba₃AlP₃. The compounds Sr₃GaAs₃ and Ba₃GaAs₃ crystallize with the Ba₃GaSb₃-type structure (Pearson symbol oP56, space group Pnma, Z = 8). Both structures are made up of isolated pairs of edge-shared AlPn₄ and GaPn₄ tetrahedra (Pn = pnictogen, i.e., P or As), separated by the alkaline-earth Sr²⁺ and Ba²⁺ cations. In both cases, there are no homoatomic bonds, hence, regardless of the slightly different atomic arrangements, both structures can be rationalized as valence-precise [AE²⁺]₃[Tr³⁺][Pn³⁻]₃, or rather [AE²⁺]₆[Tr₂Pn₆]¹²⁻, i.e., as Zintl phases.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.