The primary products in reactions of laser-ablated group 5 metal atoms with ethane were identified in argon matrix IR spectra and characterized via density functional theory computations. The second- and third-row transition metals Nb and Ta produced insertion, metallacyclopropane, vinyl trihydrido, and anionic ethylidyne complexes (CH3CH2-MH, (CH2)(2)-MH2, CH2 = CH-MH3, and CH3C MH3-), while the first-row transition metal V yielded only the insertion and metallacyclopropane products. The energetically higher ethylidenes and neutral ethylidynes (CH3CH = MH2 and CH3C = MH3) were not detected. The unique anionic ethylidynes are the most stable anionic species in the Nb and Ta systems. Evidently back-donation from the metal center to the C-C pi* orbital is stronger than that in the group 6 metal analogue but weaker than that in the corresponding group 4 metal complex. The C-M bond for the Nb and Ta ethylidyne anions is a true triple bond.