Installing Quaternary Germanium Centers in Sila-Diamondoid Cores via Skeletal Isomerization

This manuscript describes two skeletal isomerization strategies to install one to four quaternary germanium atoms in the sila-adamantane core, in a cluster analogy to precision germanium doping in silicon-germanium alloys. The first synthetic strategy embodies an inorganic approach to the single-atom skeletal editing concept recently developed for modifying organic ring structures. Here we perform a single-atom Si-to-Ge transmutation in the sila-diamondoid core by functionalizing sila-adamantane with a peripheral trimethylgermane, then inducing a sila-Wagner-Meerwein bond shift cascade that exchanges a peripheral Ge atom with a core Si atom. Next, we demonstrate the regioselective installation of up to four Ge atoms at the quaternary centers of the adamantane, where the exact SixGey stoichiometry of the SiGe adamantane can be pre-determined from precursor design. Finally, we show we selectively functionalize bridgehead Ge centers over bridgehead Si centers in the SiGe adamantanes, suggesting a path to the regioselective construction of materials with SixGey adamantanes as superatomic building blocks. As the SiGe adamantanes are molecular versions of the SixGe1-x alloy semiconductor, the disclosed synthetic approaches will broadly enable investigation into how the composition and positional substitution of SixGey diamondoid structures impact its fundamental electronic properties.