Structural evolution of triniobium carbide clusters: evidence of large Cn chains (n = 3-4) in Nb3Cn- (n = 5-10) clusters.

First-principle density functional calculations and photoelectron spectroscopy experiments show that triniobium carbide clusters exist in multiple motifs. The Nb(3)C(n)(-) (n = 5-10) series have isomers surrounding a triangular Nb(3) base while incorporating Nb-C bonding. We provide evidence of not only C(2) carbon chains but also stable isomers with previously unidentified C(3) and C(4) carbon chains in triniobium carbide clusters.