text: Along with the related organotantalum species, niobium alkylidenes were among the first Scrock carbenes studied. The first syntheses of these complexes involved addition of organolithium reagents lacking β-hydrogens into hindered Nb(V) complexes followed by α-proton elimination. As compared to tantalum alkylidenes, niobium alkylidenes are less thermally and hydrolytically stable.