Various structures of complexes of the cluster Ni-3 with 3 to 12 N-2 ligands were modeled with a gradient-corrected density functional method. The stability of different types of bonding was considered and the most stable structures of Ni-3(N-2)(x) complexes (x = 3-9, 12) were determined for neutral, cationic, and anionic systems. For the most stable structure of the neutral complex with three and six N-2 ligands, we calculated average ligand binding energies of 116 and 98 kJ/mol, respectively; the binding energy per ligand decreases with increasing number of ligand molecules. For canonical ensembles of mono- and trinuclear complexes with N-2 ligands at varying molar ratio k = [N-2]: [Ni-3], our results suggest that, in agreement with experiment, the complex Ni-3(N-2)(6) is among the dominating species at saturation; yet, at sufficiently large molar ratios k, the trinuclear complex with seven ligands, not observed in experiment, also plays an important role in the simulated distributions. It is unclear whether this partial discrepancy in the product distribution originates from complications to simulate the experimental situation or from some aspects of the experimental procedure. Coordination of more than seven N-2 ligands is predicted to lead to a partial or full destruction of the Ni-3 moieties into mononuclear N-2 ligated complexes. The type of bonding of the N-2 ligands (end-on, side-on, hapticity) was found to affect the characteristics of the complexes, e.g. the binding energy, the charge of the Ni-3 moiety, and the activation of the ligands. End-on coordination of N-2 molecules to a Ni atom of the Ni-3 unit entails the most stable type of bonding, whereas side-on coordination causes a stronger elongation of N-N bonds. The ionization potential and the electron affinity of a Ni-3 cluster were calculated to increase after association of ligands.