Figueira, Claudia A.Lopes, Patricia S.Meyrelles, RicardoGomes, Clara S. B.Gomes, Joselaine C. S.Veiros, Luís F.Gomes, Pedro T.2026-02-102026-02-102025-12-090020-1669PURE: 150358910PURE UUID: c5114e78-103a-4cac-8ad8-5eb254a63e11WOS: 001634096100001PubMed: 41364028Scopus: 105025193345PubMedCentral: PMC12818750ORCID: /0000-0003-3672-0045/work/205348064http://hdl.handle.net/10362/200202During the development of neutral aryl-nickel(II) triphenylphosphine complexes bearing bidentate 5-aryl-2-(N-aryl)formiminopyrrolyl ligands as single-component ethylene polymerization catalysts, an unexpected intramolecular C–H activation was observed. Reaction of sodium salts of ligand precursors 5-(2,6-Me2C6H3)-2-(N-2,6-R2C6H3)formiminopyrrole (R = Me I, iPr II, 3,5-(CF3)2C6H3 III) with trans-[Ni(Ar)(PPh3)2Cl] (Ar = o-C6H4Cl or C6H5) afforded unsymmetrical tridentate C,N,N’-pincer iminopyrrolyl nickel(II) complexes [Ni{κ3C,N,N’-5-(2′-CH2–6-MeC6H3)-NC4H2-2-C(H)═N-2,6-R2C6H3}(PPh3)] (R = Me 1, iPr 2, 3,5-(CF3)2C6H3 3). Complexes 1-3 and their ligand precursors were characterized using multinuclear NMR, X-ray diffraction, and elemental analysis. NMR revealed initial coexistence of tridentate C,N,N’- and bidentate N,N’-iminopyrrolyl Ni(II) complexes; at higher temperature, only the tridentate remain. DFT calculations indicated that cyclometalation proceeds via an agostic C–H interaction with the Ni center, enabling C–H activation. Thermally stable 1-3 were evaluated as single-component catalysts for ethylene polymerization (25–50 °C, 3–15 bar), both with and without Ni(COD)2 as phosphine scavenger. The resulting monomodal hyperbranched polyethylenes (HBPEs) displayed higher molecular weights and branching than those from parent bidentate 2-iminopyrrolyl phenyl-Ni(II) catalysts. These novel tridentate C,N,N’-pincer systems exhibited significantly enhanced activity and robustness. The HBPEs produced are promising as synthetic base oils for high-performance lubricants and pour-point depressants.186148082engjournal article10.1021/acs.inorgchem.5c03794https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=nova_api&SrcAuth=WosAPI&KeyUT=WOS:001634096100001&DestLinkType=FullRecord&DestApp=WOS_CPLhttps://www.scopus.com/pages/publications/105025193345