Directed Gas Phase Formation of the Elusive Silylgermylidyne Radical (H₃SiGe, X²A′′)

The previously unknown silylgermylidyne radical (H 3 SiGe; X 2 A′′) was prepared via the bimolecular gas phase reaction of ground state silylidyne radicals (SiH; X 2 Π) with germane (GeH 4 ; X 1 A 1 ) under single collision conditions in crossed molecular beams experiments. This reaction begins with the formation of a van der Waals complex followed by insertion of silylidyne into a germanium‐hydrogen bond forming the germylsilyl radical (H 3 GeSiH 2 ). A hydrogen migration isomerizes this intermediate to the silylgermyl radical (H 2 GeSiH 3 ), which undergoes a hydrogen shift to an exotic, hydrogen‐bridged germylidynesilane intermediate (H 3 Si(μ‐H)GeH); this species emits molecular hydrogen forming the silylgermylidyne radical (H 3 SiGe). Our study offers a remarkable glance at the complex reaction dynamics and inherent isomerization processes of the silicon‐germanium system, which are quite distinct from those of the isovalent hydrocarbon system (ethyl radical; C 2 H 5 ) eventually affording detailed insights into an exotic chemistry and intriguing chemical bonding of silicon‐germanium species at the microscopic level exploiting crossed molecular beams.