[(Me3Si)Si]3EtGe9Pd(PPh3), a Pentafunctionalized Deltahedral Zintl Cluster: Synthesis, Structure, and Solution Dynamics

The title compound, which has a ten-atom deltahedral cluster core of Ge9Pd, was synthesized through insertion of Pd(PPh3) into the tetrasubstituted nona-germanium cluster [(Me3Si)Si](3)EtGe9 through a reaction of the latter with Pd(PPh3)(4). This first reaction of neutral tetrasubstituted nine-atom clusters shows that they retain reactivity despite their neutral charge. The Ge9Pd core is the first that incorporates a 5-connected transition metal other than from Group VI, a noble metal in this case. Single-crystal X-ray diffraction shows that the ten-atom core is a closo-cluster with the expected shape of a bicapped square antiprism. H-1 and C-13 NMR spectroscopy show that, in contrast to the parent tetra-substituted [(Me3Si)Si]3EtGe(9), the new compound does not exhibit dynamics. Relativistic DFT calculations are used to explain the differences.