Four binary lanthanum stannides close to the 1:1 ratio of Sn:La were synthesized from mixtures of the elements. The structures of the compounds have been determined by means of single-crystal Xray data. The low temperature (α) form of LaSn (CrB-type, orthorhombic, space group Cmcm, a = 476.33(6), b = 1191.1(2), c = 440.89(6) pm, Z = 4, R1 = 0.0247), crystallizes with the CrB-type. The structure exhibits planar tin zigzag chains with a Sn-Sn bond length of 299.1 pm. In contrast to the electron precise Zintl compounds of the alkaline earth elements, additional La-Sn bonding contributions become apparent from the results of band structure calculations. In the somewhat tin-richer region, the new compound La 3 Sn 4 (orthorhombic, space group Cmcm, a = 451.45(4), b = 1190.44(9), c = 1583.8(2) pm, Z = 4, R1 = 0.0674), crystallizing with the Er 3 Ge 4 structure type, exhibits Sn 3 segments of the zigzag chains of α-LaSn together with a further Sn atom in a square planar Sn coordination with increased Sn-Sn

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