New Intermetallics YbAu2In4 and Yb2Au3In5

The intermetallic compounds YbAu2In4 and Yb2Au3In5 were obtained as single crystals in high yield from reactions run in liquid indium. Single crystal X-ray diffraction data of YbAu2In4 showed that it crystallizes as a new structure type in the monoclinic space group P 2(1)/m and lattice constants a = 7.6536(19) angstrom, b = 4.5424(11) angstrom, c = 9.591(2) angstrom and beta = 107.838(4)degrees. The YbAu2In4 compound is composed of a complex [Au2In4](3-) polyanionic network in which the rare-earth ions are embedded. Yb2Au3In5 crystallizes in the polar space group Cmc2(1) with the Y2Rh3Sn5 type structure and lattice constants a = 4.5351(9) angstrom, b = 26.824(5) angstrom, and c = 7.4641(15) angstrom. The gold and Indium atoms define a complex three-dimensional [Au3In5] network with a broad range of Au-In (2.751(2) angstrom-3.0518(16) angstrom) and In-In (3.062(3) angstrom-3.3024(19) angstrom) distances. Magnetic susceptibility measurements of YbAu2In4 revealed a transition at 25 K. Below the transition, the susceptibility of YbAu2In4 follows Curie-Weiss behavior with an effective paramagnetic moment of 0.79 mu(B)/Yb. Magnetic susceptibility measurements on Yb2Au3In5 show a mixed valent ytterbium and the magnetic moment within the linear region (<100 K) of 1.95 mu(B)/Yb. Heat capacity data for YbAu2In4 and Yb2Au3In5 give Debye temperatures of 185 and 153 K, respectively.