The structure of La3Au4In7 and its relation to the BaAl4 type

La3Au4In7 was prepared by are-melting of the elements and subsequent anneal ing at 970 K. X-ray diffraction of powders and single crystals yielded I2/m 11, mI28, a = 460.42(5) pm, b = 1389.5(1) pm, c = 1039.6(2) pm, alpha = 90. 77(1)degrees, wR2 = 0.0621, 1089F(2) values, 46 variables. The structure of La3Au4In7 is of a new type. It may be considered as a monoclinically disto rted, ordered variant of the La3Al11 type. The structural relation with the family of BaAl4 related compounds is discussed on the basis of a group-sub group scheme. The gold and indium atoms in La3Au4In7 build a three-dimensio nal [Au4In7] polyanion in which the lanthanum atoms fill distorted pentagon al and hexagonal channels. Within the polyanion short Au-In and In-In dista nces are indicative of strongly bonding Au-In and In-In interactions.