Remote Bonding in Clusters [Pd3Ge18R6]2-: Modular Bonding Model for Large Clusters via Principal Interacting Orbital Analysis

Main group cluster compounds have attracted increasing attention in the past decades. Despite recent developments in their synthesis, the description of their electronic structures is usually limited to simply applying Wade's rule originally developed for borane compounds. This traditional approach is once again challenged by two recently reported group 14 metalloid clusters in the form of [Pd3Ge18R6](2-). In this work, we put forward a modular bonding model for these two clusters, via principal interacting orbital (PIO) analysis. The site preference for six substituents has also been analyzed.