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Abstract:
Investigations in the ternary system Eu-Al-Pt led to the discovery of Eu4Al13Pt9, a new representative exhibiting a coloring variant of the Ho4Ir13Ge9 type structure. The orthorhombic structure was refined based on single crystal X-ray diffraction data (Pmmn, Wyckoff sequence e 9 b 3 a 5, a = 415.38(1), b = 1149.73(2), c = 1994.73(5) pm, wR2 = 0.0622, 1901 F 2 values, 88 variables) and full atomic ordering was observed for all atoms. The structure features a complex [Al13Pt9] δ- network with the Eu atoms occupying hexagonal prismatic cavities. The bonding situation of this new platinide was investigated via quantum-chemical calculations. According to Density Functional Theory (DFT) the title compound has to be described as a polar intermetallic material with a covalently bonded [Al13Pt9] δ- polyanion showing strong Pt-Al alongside weak Al-Al and Pt-Pt bonding and Eu cations in the cavities. © 2023 Walter de Gruyter GmbH, Berlin/Boston 2023.