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Unexpected Formation of Neutral Alkyl-Ni(II) Complexes Bearing Unsymmetrical C,N,N’-Pincer Iminopyrrolyl Ligands via Intramolecular C–H Bond Activation

2025-12-09Artigo científico Acesso aberto
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dc.contributor.authorFigueira, Claudia A.
dc.contributor.authorLopes, Patricia S.
dc.contributor.authorMeyrelles, Ricardo
dc.contributor.authorGomes, Clara S. B.
dc.contributor.authorGomes, Joselaine C. S.
dc.contributor.authorVeiros, Luís F.
dc.contributor.authorGomes, Pedro T.
dc.contributor.institutionLAQV@REQUIMTE
dc.contributor.institutionDQ - Departamento de Química
dc.contributor.pblACS - American Chemical Society
dc.date.accessioned2026-02-10T14:39:01Z
dc.date.available2026-02-10T14:39:01Z
dc.date.issued2025-12-09
dc.description.abstractDuring 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.en
dc.description.versionpublishersversion
dc.description.versionpublished
dc.format.extent18
dc.format.extent6148082
dc.identifier.doi10.1021/acs.inorgchem.5c03794
dc.identifier.issn0020-1669
dc.identifier.otherPURE: 150358910
dc.identifier.otherPURE UUID: c5114e78-103a-4cac-8ad8-5eb254a63e11
dc.identifier.otherWOS: 001634096100001
dc.identifier.otherPubMed: 41364028
dc.identifier.otherScopus: 105025193345
dc.identifier.otherPubMedCentral: PMC12818750
dc.identifier.otherORCID: /0000-0003-3672-0045/work/205348064
dc.identifier.urihttp://hdl.handle.net/10362/200202
dc.identifier.urlhttps://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=nova_api&SrcAuth=WosAPI&KeyUT=WOS:001634096100001&DestLinkType=FullRecord&DestApp=WOS_CPL
dc.identifier.urlhttps://www.scopus.com/pages/publications/105025193345
dc.language.isoeng
dc.peerreviewedyes
dc.titleUnexpected Formation of Neutral Alkyl-Ni(II) Complexes Bearing Unsymmetrical C,N,N’-Pincer Iminopyrrolyl Ligands via Intramolecular C–H Bond Activationen
dc.title.subtitleA Distinct Type of Single-Component Ethylene Polymerization Catalystsen
dc.typejournal article
degois.publication.firstPage24479
degois.publication.issue50
degois.publication.lastPage24496
degois.publication.titleInorganic Chemistry
degois.publication.volume64
dspace.entity.typePublication
rcaap.rightsopenAccess

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