Reported here are the synthesis and characterization of ortho-nickelated complexes derived from phosphinite ligands and investigated as model compounds in the development of C−H functionalization strategies for arenol substrates. Reaction of i-Pr 2 POPh with 0.6 equiv of [(i-PrCN)NiBr 2 ] n and 0.8 equiv of NEt 3 in toluene (100°C, 36 h) gave the yellow, monomeric cyclometalated complex trans-{κ 2 P,C-C 6 H 4 OP(iPr) 2 }Ni(i-Pr 2 POPh)Br (3a) in 93% yield. The closely related yellow-orange dimeric species [{κ 2 P,C-C 6 H 4 OP(i-Pr) 2 }Ni(μ-Br)] 2 (4a) was obtained in 70% yield when i-Pr 2 POPh was treated with 2 equiv each of the Ni precursor and NEt 3 . These complexes have been characterized fully and shown to interconvert in the presence of excess ligand (4a → 3a) or excess Ni precursor (3a → 4a). Treatment of 3a or 4a with benzyl bromide at 90°C over extended periods led to benzylation of the Ni−aryl moiety in these complexes. Examination of the cyclometalation pathway for i-Pr 2 POPh has shown that the first species formed from its ambient-temperature reaction with [(iPrCN)NiBr 2 ] n is trans-(i-Pr 2 POPh) 2 NiBr 2 (2a). NMR studies showed that 2a undergoes a rapid ligand exchange at room temperature, which can be slowed down at −68°C; this fluxional process shifts in the presence of NEt 3 , implying the partial formation of an amine adduct. Heating toluene mixtures of 2a and NEt 3 at 90°C for 38 h led to the formation of 3a via C−H nickelation. That phosphinite dissociation from 2a precedes the C−H nickelation step is implied by the observation that the formation of 3a is hindered in the presence of excess i-Pr 2 POPh. The impact of phenol ring substituents on the C−H nickelation rate was probed by preparing substituted derivatives of 2a, trans-(4-R-C 6 H 4 OP(i-Pr 2 )} 2 NiBr 2 (R = OMe (2b), Me (2c), COOMe (2d)), and measuring their relative rates of C−H nickelation. These studies showed that the formation of cyclonickelated products is favored in the order COOMe < Me < OMe, which is consistent with an electrophilic nickelation mechanism. Studying the C−H nickelation of 3-F-C 6 H 4 OP(i-Pr 2 ) allowed us to establish that metalation is favored at the para position with respect to F (85:15).