Eclipsed- and Staggered-[Ge_(18)Pd_3{E~iPr_3}_6]~(2-) (E = Si, Sn): Positional Isomerism in Deltahedral Zintl Clusters

摘要

We report the synthesis and characterization of the cluster anions [Ge_(18)Pd_3{Si~iPr_3}_6]~(2-) (1) with a core of face-fused twinned icosahedra, Ge_(18)Pd_3, and two sets of three ~iPr_3Si-substituents positioned in "eclipsed" geometry. The new anion is a positional isomer of the recently reported "staggered" stannyl-ligated counterpart [Ge_(18)Pd_3{Sn~iPr_3}_6]~(2-) (2), showing the possibility to find such positional isomerism in Zintl clusters. Both anions are characterized by single-crystal X-ray diffraction, ~1H and ~(13)C NMR, and negative-ion ESI-MS. Using relativistic DFT calculations, we elucidate and discuss the reasons for the different positioning of the ligands in the stannyl- and silyl-functionalized species.