We present a theoretical investigation on the structural evolution and bonding properties of PdnC2-/0 (n = 1-7) clusters using density functional theory calculations. The results showed that the two C atoms in Pd1-7C2-/0 directly interact with each other to form a C-C bond, except for neutral Pd6C2. The Pd atoms can be viewed as an integral cluster unit interacting with C-2 frameworks and have very weak interactions with each other. Interestingly, Pd6C2 neutral has a D-3d symmetric bicapped trigonal antiprism structure with the two C atoms located at the apex positions and shows cy plus it double delocalized bonding patterns. (C) 2018 Elsevier B.V. All rights reserved.