This report describes the synthesis and characterization of new pincer-type complexes of divalent and trivalent nickel. Refluxing toluene mixtures of NiBr2(CH3CN) n and the unsymmetrical pincer-type ligands Ph-POCHNimine-R gave (Ph-POCNimine-R)Ni(II)Br in good yields (Ph-POCHNimine-R = 1-(Ph2PO),3-(CHNR)C6H4; R = Bn, 1; Ph, 2; t-Bu, 3; Cy, 4). The C–H nickelation step involved in these syntheses is facilitated in the presence of NEt3. Treating compounds 1–4 with Br2, I2, N-bromosuccinimide (NBS) and N-chlorosuccinimide appears to bring about the desired one-electron oxidation of the Ni(II) center in these complexes, but the putative trivalent species decompose over time and could not be isolated. One of the decomposition products obtained in the Br2 reaction was identified as the zwitterionic compound Br3Ni(II){κO-(E)-N-(3-((diphenylphosphoryl)oxy)benzylidene)benzenaminium}, 5. To identify the factors that are important for isolation of stable trivalent derivatives, we prepared the divalent precursors (i-Pr-POCNimine-Ph)NiX (X= Br, 6, and NCS, 9) and studied their reactions with various oxidants. Whereas treatment of 6 with Br2 or NBS gave the target 17-electron complex (i-Pr-POCNimine-Ph)Ni(III)Br2 (7), no mixed-ligand trivalent complexes of the type (i-Pr-POCNimine-Ph)Ni(III)Br(X) could be isolated from reactions of (i-Pr-POCNimine-Ph)Ni(NCS) (9) with NBS or of 6 with N-chlorosuccinimide. The latter reaction gave a complex mixture from which was isolated a paramagnetic, trinuclear compound (8) composed of octahedral Ni(II) units featuring μ2-Cl and μ2,κO,κN-succinimide fragments. The solid state structures of all new complexes 2-9 have been elucidated by X-ray crystallography.