Compounds of Germanium and Tin, 2l . A Tetraaryldigermene with a Short Germanium‐Germanium Double Bond and a Nearly Planar Environment of Both Germanium Atoms

Treatment of GeCl 2 · dioxane with the Grignard reagent RMgBr (R=2‐ t Bu‐4,5,6‐Me 3 C 6 H) furnishes the tetraaryldigermene R 2 GeGeR 2 ( 8 ). X‐ray structure‐analysis of 8 reveals a short GeGe double bond, a nearly planar environment of both germanium atoms and extremely widened CGeC angles of 128°. In solution, 8 dissociates into two germylene molecules R 2 Ge, which can be trapped with oxygen or by [4+1] cycloaddition reactions with 1,4‐dihetero‐1,3‐dienes. A similar cycloadduct of a stannylene wa obtained by thermolysis of (R ′ 2 Sn) 3 (R′=2,4,6‐ i Pr 3 C 6 H 2 ), in the presence of a 1,4‐diazabutadiene and characterized by an X‐ray structure‐analysis.