Bond-stretch isomerism in 2-chalcogen-trimetallabicyclo[1.1.0]butane derivatives

► The bond-stretch isomers of heavy bicyclo[1.1.0]butane derivatives are examined. ► We found and investigated the electronic structure of a new anti isomer. ► It is a promising synthetic target in germanium bridged bicycle compounds. ► Anti isomer is preferable with bulky bridgehead substituents having carbon contact atom.