Gas-Phase Preparation of 1-Germavinylidene (H 2 CGe; X 1 A 1 ), the Isovalent Counterpart of Vinylidene (H 2 CC; X 1 A 1 ), via Non-adiabatic Dynamics through the Elementary Reaction of Ground State Atomic Carbon (C; 3 P) with Germane (GeH 4 ; X 1 A 1 ).

1-Germavinylidene (H 2 CGe; X 1 A 1 ), the germanium analogue of vinylidene (H 2 CC; X 1 A 1 ), was prepared via a directed gas-phase synthesis through the bimolecular reaction of ground state atomic carbon (C; 3 P) with germane (GeH 4 ; X 1 A 1 ) under single-collision conditions. The reaction commences with the barrierless insertion of carbon into the Ge-H bond followed by intersystem crossing from the triplet to singlet surface and migration of atomic hydrogen to germylene (H 2 GeCH 2 ), which predominantly decomposes via molecular hydrogen loss to 1-germavinylidene (H 2 CGe; X 1 A 1 ). Therefore, the replacement of a single carbon atom in the acetylene-vinylidene system by germanium critically impacts the chemical bonding, molecular structure, and thermodynamic stability of the carbene-type structures favoring 1-germavinylidene (H 2 CGe) over germyne (HGeCH) by 160 kJ mol -1 . Hence, the carbon-germane system represents a benchmark in the exploration of the chemistries of main group 14 elements with germanium-bearing systems showing few similarities with the isovalent carbon system.