C-N Coupling in N Fixation by the Ditantalum Carbide Cluster Anions TaC.

The construction of C-N bonds by the direct incorporation of dinitrogen (N) instead of ammonia (NH) into active species is particularly desirable but has been rarely reported. Herein, a ditantalum carbide cluster anion (TaC) capable of cleaving the N≡N bond and constructing a C-N bond under mild conditions has been identified using mass spectrometry, photoelectron imaging spectroscopy, and quantum-chemical calculations. The photoelectron spectrum of TaCN is remarkably different from that of TaC and matches the simulated spectrum of the TaCN species with an end-on-bonded CN unit. The formation of the C-N bond has also been supported by the CN fragment observed in the collision-induced dissociation of TaCN. The exceptional reactivity of TaC is ascribed to the low-valent metal center serving as an electron reservoir. This study provides a non-NH route to construct C-N bonds by incorporating N into carbide compounds to produce nitrogenous species.