The crystal structure, electronic, and magnetic properties of NaPd₃Ge₂

Crystals of NaPd₃X₂, (X = Si, Ge, Sn) were synthesized and their crystal structures investigated by single crystal X-ray diffraction. The previously reported structures of NaPd₃Si₂ and NaPd₃Sn₂ were confirmed. NaPd₃Ge₂ was found to have a different unit cell from that originally reported; therefore the structure was solved. It is an orthorhombically distorted version of the hexagonal CeCo₃Be₂-type structure, in space group Imma, with cell parameters a = 7.244(1) Å, b = 9.938(1) Å, c = 5.767(2) Å. The originally reported cell is explained through triple twinning of the true cell. The structure of NaPd₃Ge₂ fits the trend of decreasing X-X dimerization as a function of increasing period from Si-Sn. All three compounds are metals showing weak diamagnetism with increasing resistivity from NaPd₃Si₂-NaPd₃Sn₂; no superconductivity is observed down to 2 K.