Experimental Evidence for Linear Metal–Azido Coordination: The Binary Group 5 Azides [Nb(N₃)₅], [Ta(N₃)₅], [Nb(N₃)₆]⁻, and [Ta(N₃)₆]⁻, and 1:1 Acetonitrile Adducts [Nb(N₃)₅(CH₃CN)] and [Ta(N₃)₅(CH₃CN)]

Straightened out: The first binary Group 5 azides were prepared by fluorido–azido exchange starting from MF5 (M=Nb, Ta) and characterized by vibrational spectroscopy. The crystal structure of the acetonitrile adduct [Nb(N3)5(CH3CN)] (see picture) provides the first experimental evidence for the existence of linear M-N-N coordination for azido complexes.