{"id":{"repo_id":"penn","oai_identifier":"oai:repository.upenn.edu:20.500.14332/30946"},"canonical_url":"https://search.dev.ndltd.org/etd/penn/oai:repository.upenn.edu:20.500.14332/30946","repository":{"repo_id":"penn","name":"University of Pennsylvania","base_url":"https://repository.upenn.edu/server/oai/request"},"display":{"title":"Synthesis, Characterization And Reactivity Studies Of Nickel Complexes Supported By A Phosphinimine-Based Pincer Ligand","abstract":"Tridentate pincer-type ligands offer both electronic and steric flexibility and have been used to stabilize highly reactive species, including late transition metal complexes with metal–ligand multiple bonds. Herein, we report a series of novel nickel complexes supported by a pincer-type bis(phosphinimine) ligand framework {HN(1,2-C6H4N=PPh2Me)2}. Metalation of the ligand onto NiCl2(dme) formed the nickel chloride species [(1,2-C6H4N=PPh2Me)2N]NiCl, which demonstrated geometric isomerism in solution. Photolysis of the azide congener [(1,2-C6H4N=PPh2Me)2N]NiN3 resulted in the C−H activation of a methyl group in the phosphinimine group, generating a nickel metallacycle complex [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni, which could also be generated upon reduction of a phenoxide complex [(1,2-C6H4N=PPh2Me)2N]NiOPh. Further deprotonation of this nickel metallacycle occurred on the second methyl group and afforded a nickel dialkyl metallacycle [N(1,2-C6H4N=PPh2CH2)2Ni](Na). Protonolysis of this complex reformed [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni, illustrating the chemical reversibility of this process. The redox non-innocence of the phosphinimine pincer ligand was then explored. Oxidation of [(1,2-C6H4N=PPh2Me)2N]NiOPh was primarily ligand-centered, as supported by EPR, UV-vis and DFT studies. Two-electron oxidation of [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni generated a diamagnetic compound, which was proposed to be a nitrenium ion bound Ni(II) complex. [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni also exhibited versatile reactivity toward H−E (E= O, S) bond activation via metal-ligand cooperation (MLC). Of particular interest is the ability of this complex to formally abstract a sulfur atom from triphenylmethyl thiol with the concomitant formation of triphenylmethane. The formation of a terminal nickel sulfide [(1,2-C6H4N=PPh2Me)2N]Ni=S as an intermediate was proposed. Experimental results suggested that the reaction mechanism involved an intermolecular S-atom transfer from the proposed nickel sulfide intermediate to [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni to form a S-atom insertion product, [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2S)]Ni.","abstract_html":"Tridentate pincer-type ligands offer both electronic and steric flexibility and have been used to stabilize highly reactive species, including late transition metal complexes with metal–ligand multiple bonds. Herein, we report a series of novel nickel complexes supported by a pincer-type bis(phosphinimine) ligand framework {HN(1,2-C6H4N=PPh2Me)2}. Metalation of the ligand onto NiCl2(dme) formed the nickel chloride species [(1,2-C6H4N=PPh2Me)2N]NiCl, which demonstrated geometric isomerism in solution. Photolysis of the azide congener [(1,2-C6H4N=PPh2Me)2N]NiN3 resulted in the C−H activation of a methyl group in the phosphinimine group, generating a nickel metallacycle complex [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni, which could also be generated upon reduction of a phenoxide complex [(1,2-C6H4N=PPh2Me)2N]NiOPh. Further deprotonation of this nickel metallacycle occurred on the second methyl group and afforded a nickel dialkyl metallacycle [N(1,2-C6H4N=PPh2CH2)2Ni](Na). Protonolysis of this complex reformed [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni, illustrating the chemical reversibility of this process. The redox non-innocence of the phosphinimine pincer ligand was then explored. Oxidation of [(1,2-C6H4N=PPh2Me)2N]NiOPh was primarily ligand-centered, as supported by EPR, UV-vis and DFT studies. Two-electron oxidation of [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni generated a diamagnetic compound, which was proposed to be a nitrenium ion bound Ni(II) complex. [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni also exhibited versatile reactivity toward H−E (E= O, S) bond activation via metal-ligand cooperation (MLC). Of particular interest is the ability of this complex to formally abstract a sulfur atom from triphenylmethyl thiol with the concomitant formation of triphenylmethane. The formation of a terminal nickel sulfide [(1,2-C6H4N=PPh2Me)2N]Ni=S as an intermediate was proposed. Experimental results suggested that the reaction mechanism involved an intermolecular S-atom transfer from the proposed nickel sulfide intermediate to [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni to form a S-atom insertion product, [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2S)]Ni.","abstract_has_math":false,"creators":["Xing, Xiujing"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Neil Tomson"],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020","date_published":"2020","updated_at":"2026-07-24T03:46:44Z","subjects":[],"languages":["en"],"rights":["Xiujing Xing"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://repository.upenn.edu/handle/20.500.14332/30946","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Neil Tomson"]},{"key":"dc:creator","label":"Author","values":["Xing, Xiujing"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2023-05-18T01:06:17.000"]},{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2023-05-22T17:55:07Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2024-01-06T00:00:00Z"]},{"key":"dc:date.issued","label":"Date","values":["2020"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation/Thesis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Xiujing Xing"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://repository.upenn.edu/handle/20.500.14332/30946"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Tridentate pincer-type ligands offer both electronic and steric flexibility and have been used to stabilize highly reactive species, including late transition metal complexes with metal–ligand multiple bonds. Herein, we report a series of novel nickel complexes supported by a pincer-type bis(phosphinimine) ligand framework {HN(1,2-C6H4N=PPh2Me)2}. Metalation of the ligand onto NiCl2(dme) formed the nickel chloride species [(1,2-C6H4N=PPh2Me)2N]NiCl, which demonstrated geometric isomerism in solution. Photolysis of the azide congener [(1,2-C6H4N=PPh2Me)2N]NiN3 resulted in the C−H activation of a methyl group in the phosphinimine group, generating a nickel metallacycle complex [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni, which could also be generated upon reduction of a phenoxide complex [(1,2-C6H4N=PPh2Me)2N]NiOPh. Further deprotonation of this nickel metallacycle occurred on the second methyl group and afforded a nickel dialkyl metallacycle [N(1,2-C6H4N=PPh2CH2)2Ni](Na). Protonolysis of this complex reformed [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni, illustrating the chemical reversibility of this process. The redox non-innocence of the phosphinimine pincer ligand was then explored. Oxidation of [(1,2-C6H4N=PPh2Me)2N]NiOPh was primarily ligand-centered, as supported by EPR, UV-vis and DFT studies. Two-electron oxidation of [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni generated a diamagnetic compound, which was proposed to be a nitrenium ion bound Ni(II) complex. [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni also exhibited versatile reactivity toward H−E (E= O, S) bond activation via metal-ligand cooperation (MLC). Of particular interest is the ability of this complex to formally abstract a sulfur atom from triphenylmethyl thiol with the concomitant formation of triphenylmethane. The formation of a terminal nickel sulfide [(1,2-C6H4N=PPh2Me)2N]Ni=S as an intermediate was proposed. Experimental results suggested that the reaction mechanism involved an intermolecular S-atom transfer from the proposed nickel sulfide intermediate to [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni to form a S-atom insertion product, [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2S)]Ni."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Doctor of Philosophy (PhD)"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Synthesis, Characterization And Reactivity Studies Of Nickel Complexes Supported By A Phosphinimine-Based Pincer Ligand"]}]}],"canonical_facts":{"dc:contributor.advisor":["Neil Tomson"],"dc:creator":["Xing, Xiujing"],"dc:date":["2023-05-18T01:06:17.000"],"dc:date.accessioned":["2023-05-22T17:55:07Z"],"dc:date.available":["2024-01-06T00:00:00Z"],"dc:date.issued":["2020"],"dc:description.abstract":["Tridentate pincer-type ligands offer both electronic and steric flexibility and have been used to stabilize highly reactive species, including late transition metal complexes with metal–ligand multiple bonds. Herein, we report a series of novel nickel complexes supported by a pincer-type bis(phosphinimine) ligand framework {HN(1,2-C6H4N=PPh2Me)2}. Metalation of the ligand onto NiCl2(dme) formed the nickel chloride species [(1,2-C6H4N=PPh2Me)2N]NiCl, which demonstrated geometric isomerism in solution. Photolysis of the azide congener [(1,2-C6H4N=PPh2Me)2N]NiN3 resulted in the C−H activation of a methyl group in the phosphinimine group, generating a nickel metallacycle complex [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni, which could also be generated upon reduction of a phenoxide complex [(1,2-C6H4N=PPh2Me)2N]NiOPh. Further deprotonation of this nickel metallacycle occurred on the second methyl group and afforded a nickel dialkyl metallacycle [N(1,2-C6H4N=PPh2CH2)2Ni](Na). Protonolysis of this complex reformed [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni, illustrating the chemical reversibility of this process. The redox non-innocence of the phosphinimine pincer ligand was then explored. Oxidation of [(1,2-C6H4N=PPh2Me)2N]NiOPh was primarily ligand-centered, as supported by EPR, UV-vis and DFT studies. Two-electron oxidation of [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni generated a diamagnetic compound, which was proposed to be a nitrenium ion bound Ni(II) complex. [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni also exhibited versatile reactivity toward H−E (E= O, S) bond activation via metal-ligand cooperation (MLC). Of particular interest is the ability of this complex to formally abstract a sulfur atom from triphenylmethyl thiol with the concomitant formation of triphenylmethane. The formation of a terminal nickel sulfide [(1,2-C6H4N=PPh2Me)2N]Ni=S as an intermediate was proposed. Experimental results suggested that the reaction mechanism involved an intermolecular S-atom transfer from the proposed nickel sulfide intermediate to [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2)]Ni to form a S-atom insertion product, [(1,2-C6H4N=PPh2Me)N(1,2-C6H4N=PPh2CH2S)]Ni."],"dc:description.degree":["Doctor of Philosophy (PhD)"],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["https://repository.upenn.edu/handle/20.500.14332/30946"],"dc:language":["en"],"dc:rights":["Xiujing Xing"],"dc:title":["Synthesis, Characterization And Reactivity Studies Of Nickel Complexes Supported By A Phosphinimine-Based Pincer Ligand"],"dc:type":["Dissertation/Thesis"]},"updated_at":"2026-07-24T03:46:44Z"}