1,7‐Digallatetracarborane: Between Nucleophilic closo ‐Cluster and “Inverse Sandwich” Digallylene

This manuscript describes the synthesis and chemistry of an unprecedented carborane cluster of low‐valent main‐group elements with a unique structural motif. On the basis of a dianionic borole π‐ligand platform (L = [R 5 (C 4 B)] 2− ) an “inverse sandwich”, Janus‐type digallylene complex L(Ga +I ) 2 featuring two nucleophilic Ga(I) ions was accessed. This compound can also be described as a closo ‐type 1,7‐digallatetracarborane cluster. Preliminary reactivity studies on this new compound class have been conducted. Assessment of Lewis‐basicity in coordination chemistry with transition metals and main group Lewis‐acids indicate electronic communication between the Ga‐atoms. Oxidation with free borole (L) gives rise to bent digallocene L(Ga +II )–(Ga +II )L, the first group 13 element‐based dimetallocene‐type compound. Examples demonstrate that L(Ga +I ) 2 can behave as both a discrete digallacarborane cluster and a bis‐gallylene π‐complex capable of releasing Ga + .