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

Abstract

Abstract 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.