Eight new rare-earth metal-lithium-germanides belonging to the [REGe(2)](n)[RELi(2)Ge](m) homologous series have been synthesized and structurally characterized by single-crystal X-ray diffraction. The structures of the title compounds can be rationalized as linear intergrowths of imaginary RELi(2)Ge (MgAl(2)Cu structure type) and REGe(2) (AlB(2) structure type) slabs. The compounds with general formula RE(7)Li(8)Ge(10) (RE = La-Nd, Sm), i.e., [REGe(2)](3)[RELi(2)Ge](4), crystallize in the orthorhombic space group Cmmm (No. 65) with a new structure type. Similarly, the compounds with general formula RE(11)Li(12)Ge(16) (RE = Ce-Nd), i.e., [REGe(2)](5)[RELi(2)Ge](6), crystallize in the orthorhombic space group Immm (No. 71) also with its own structure type. Temperature-dependent DC magnetization measurements indicate Curie-Weiss paramagnetism in the high-temperature regime and hint at complex magnetic ordering at low temperatures. The measured effective moments are consistent with RE(3+) ground states in all cases. The experimental results have been complemented by tight-binding linear muffin-tin orbital (TB-LMTO) electronic structure calculations.
Synthesis, Crystal Chemistry, and Magnetic Properties of RE 7 Li 8 Ge 10 and Ln11Li12Ge16 (Ln: La-Nd, Sm): New Members of the [LnGe2]n[LnLi2Ge]m Homologous Series. -The title compounds are prepared from stoichiometric mixtures of the elements (Nb tubes, 1223-1273 K, 5 h) and characterized by powder and single crystal XRD, magnetic measurements, and TB-LMTO-ASA calculations. Their structures can be rationalized as linear intergrowths of imaginary LnLi 2 Ge (MgAl 2 Cu structure type) and LnGe2 (AlB2 structure type) slabs. Ln7Li8Ge10 (Ln: La-Nd, Sm) compounds crystallize in the orthorhombic space group Cmmm with Z = 2, and the compounds Ln11Li12Ge16 (Ln: Ce-Nd) crystallize in the orthorhombic space group Immm with Z = 2. Ln7Li8Ge10 (Ln: Ce, Pr) exhibit Curie-Weiss paramagnetism in the high-temperature regime. -(GUO, S.-P.; YOU, T.-S.; JUNG, Y.-H.; BOBEV*, S.; Inorg. Chem. 51 (2012) 12, 6821-6829, http://dx.doi.org/10.1021/ic300566x ; Dep. Chem. Biochem., Univ. Del., Newark, DE 19716, USA; Eng.) -W. Pewestorf 38-003
A new polar intermetallic compound with a novel structure type has been synthesized and characterized by both powder and single-crystal X-ray diffraction. Ca(4)InGe(4) crystallizes in the monoclinic crystal system (space group C2/c, Z = 4, Pearson symbol mS36) with five crystallographically unique atomic positions in the asymmetric unit. The corresponding lattice parameters at 200(2) K are a = 18.452(8) Å, b = 5.819(2) Å, c = 8.339(3) Å, and β = 99.330(6)°. The overall crystal structure can be described as a linear intergrowth of two imaginary fragments--Ca(2)InGe(2) with the Gd(2)AlGe(2) type- and CaGe with the FeB type-structures. Another way to rationalize the bonding is to focus on the polyanionic framework, which in this case is made up of unique nets of "seesaw"-shaped [InGe(4)] units. They are interconnected via Ge-Ge dimers into an open three-dimensional framework with Ca(2+) cations occupying the voids within it. Tight-binding linear muffin-tin orbital (LMTO) calculations provide a rationale for the unique local coordination geometry around In and the two distinct types of Ge-Ge bond distances.
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