Crystalline Silagermenides as Powerful Synthons: Unraveling π‐Bonding and Lone Pair Effects in the Multiple Bonds of Heavier Main Group Analogs of the Vinyl Anion

Compared to common vinyl anions, their heavier heteronuclear analog, silagermenides [R ₂ Si═GeR]ˉ, remain exceedingly rare. Herein, we present a systematic investigation of silagermenides, synthesized via a straightforward desilylation route. We delve into the bonding characteristics, revealing a weak, polarized Si─Ge π bond with a significant nonbonded lone pair character at the β‐Si position. This β‐Si exhibits predominantly nucleophilic behavior, while the α‐Ge position demonstrates subtly electrophilic tendencies, despite the presence of a vinylic, formally anionic Ge atom. This leads to the formation of silagermenide complexes in an unprecedented η ² coordination mode, as well as various silagermenes and germylenes with unconventional substituents. We also document the facile cleavage of the ambiphilic Si═Ge double bond, resulting in the transfer of a formal doubly reduced silylene and a formal germyliumylidene. Our findings expand the understanding of heavier main group analogs of the vinyl anion, with important implications for their synthesis and reactivity.