Reactivity of a Methylene‐Bridged 1,3‐Bis(germylene) in Dynamic Equilibrium with Its Dimer

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We report the properties and reactivity of an unprecedented methylene‐bridged 1,3‐bis(germylene) derivative. In the solid state, it undergoes dimerization to afford a 1,2,4,5‐tetragermacyclohexa‐1,4‐diene derivative (Ge 4 CHD). Moreover, theoretical calculations on Ge 4 CHD reveal σ*–π interactions between the two π orbitals (Ge═Ge) and the CH σ* orbital. This interaction is confirmed by a significant red shift in the solid‐state UV–vis spectrum. In contrast to the behavior in the solid state, the Ge 4 CHD derivative dissociates in solution into a methylene‐bridged 1,3‐bis(germylene) derivative. The resultant 1,3‐bis(germylene) derivative reacted with S 8 to form a novel cage compound containing three S and two Ge atoms. On the other hand, in the reaction with triphenylphosphine sulfide, the in situ generated 2‐thia‐1,3‐digermabicyclo[1.1.0]butane derivative activated the benzene solvent, leading to the formation of a [2 + 2] cycloaddition product. Additionally, the 1,3‐bis(germylene) derivative reacted with 4‐dimethylaminopyridine (DMAP) to form a three‐membered ring. Its structural parameters and the results of theoretical calculations indicated the zwitterionic character.