Crystallographic methods

Suitable crystals from the [K(2,2,2-crypt)]₄{(Ge₉)₂[η⁶-Ge(PdPPh₃)₃]} were selected for X-ray diffraction analyses. Crystallographic data were collected on a Rigaku XtalAB Pro MM007 DW diffractometer (Cu–Mo Kα radiation) at 100 K. The structure of the crystal was solved using direct methods and then refined using SHELXL-2014 and Olex2^50–52, in which all the non-hydrogen atoms were refined anisotropically. All hydrogen atoms of organic groups were rationally placed by geometrical considerations. The K2 and K8 were refined anisotropically and show an abnormal thermal motion that could not be resolved by using restraints. The limitation of data quality leads to the low bond precision on C–C bonds, and large cell volume also makes it not easy to obtain better data. The uncoordinated solvent molecules could not be modeled properly, so the PLATON SQUEEZE procedure was used during the refinement to remove the solvent molecules⁵³.