A novel bidentate ligand featuring an N-heterocyclic phosphenium cation (NHP+) linked to a phosphine side arm is used to explore the coordination chemistry of NHP+ ligands with nickel. Direct P-Cl bond cleavage from a chlorophosphine precursor [PP]-Cl (1) by Ni(COD)(2) affords the asymmetric bimetallic complex [Cl2Ni(mu-PP)(2)Ni] (2) via a nonoxidative process. Abstraction of the halide with either NaBPh4 or K[B(C6F5)(4)] prior to metal coordination to form the free phosphenium ligand [PP](+) in situ, followed by coordination to Ni(COD)(2), afforded the halide-free Ni-0 complexes [(PP)Ni-(COD)] [B(C6F5)(4)] (4) and [(PP)Ni(COD)][BPh4] (5). Chloride abstraction from 1 is problematic in the presence of a PF6- counterion, however, as evident by the formation of [(PP)Ni(PP-F)] [PF6] (3). The COD ligand in 5 can be readily displaced with PMe3 or PPh3 to afford [(PP)NiL2] [BPh4] (L = PMe3 (6), PPh3 (7)). Complexes 2-7 feature planar geometries about the NHP+ phosphorus atom and unusually short Ni-P distances, indicative of multiple bonding resulting from both P -> Ni sigma donation and Ni -> P pi backbonding. This bonding description is supported by theoretical studies using natural bond orbital analysis.