Ab initio study of mechanism of forming a spiro-Ge-heterocyclic ring compound from H2GeGe: and formaldehyde

► Mechanism of cycloaddition between H2GeGe: and formaldehyde has been investigated. ► π Orbital and 4p unoccupied orbital of Ge: in H2GeGe: are object in cycloaddition. ► [2 + 2] Cycloaddition to form a four-membered Ge-heterocyclic ring germylene. ► It further reacts with formaldehyde to form a spiro-Ge-heterocyclic ring compound.