{"doi":"10.1021/jacs.4c11751","title":"Synthesis, Structure, and Redox Reactivity of Ni Complexes Bearing a Redox and Acid–Base Non-innocent Ligand with Ni<sup>II</sup>, Ni<sup>III</sup>, and Ni<sup>IV</sup> Formal Oxidation States","abstract":"A series of Ni complexes bearing a redox and acid–base noninnocent tetraamido macrocyclic ligand, H 4 -(TAML-4) {H 4 -(TAML-4) = 15,15-dimethyl-5,8,13,17-tetrahydro-5,8,13,17-tetraaza-dibenzo[ a,g ]cyclotridecene-6,7,14,16-tetraone}, with formal oxidation states of Ni II, Ni III, and Ni IV were synthesized and characterized structurally and spectroscopically. The X-ray crystallographic analysis of the Ni complexes revealed a square planar geometry, and the [Ni(TAML-4)] complex with the formal oxidation state of Ni IV was characterized to be [Ni III (TAML-4 •+ )] with the oxidation state of the Ni III ion and the one-electron oxidized TAML-4 ligand, TAML-4 •+ . The Ni III oxidation state and the TAML-4 radical cation ligand, TAML-4 •+, were supported by X-ray absorption spectroscopy and density functional theory calculations. The reversible interconversions between [Ni II (TAML-4)] 2– and [Ni III (TAML-4)] − and between [Ni III (TAML-4)] − and [Ni III (TAML-4 •+ )] were demonstrated in spectroelectrochemical measurements as well as in chemical oxidation and reduction reactions. The reactivities of [Ni III (TAML-4)] − and [Ni III (TAML-4 •+ )] were then investigated in hydride transfer reactions using NADH analogs. Hydride transfer from 9,10-dihydro-10-methylacridine (AcrH 2 ) to [Ni III (TAML-4 •+ )] was found to proceed via electron transfer (ET) from AcrH 2 to [Ni III (TAML-4 •+ )] with no deuterium kinetic isotope effect ( k H / k D = 1.0(2)). In contrast, hydride transfer from AcrH 2 to [Ni III (TAML-4)] − proceeded much more slowly via a concerted proton-coupled electron transfer (PCET) process with k H / k D = 7.0(5). In the latter reaction, an electron and a proton were transferred to the Ni III center and the TAML-4 ligand, respectively. The mechanisms of the ET by [Ni III (TAML-4 •+ )] and the concerted PCET by [Ni III (TAML-4)] − were ascribed to the different redox potentials of the Ni complexes.","journal":"Journal of the American Chemical Society","year":2025,"id":522613,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":4,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9489,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":699360,"name":"Hyeongtaek Lim","orcid":"0000-0003-3470-8296","position":1,"is_corresponding":false},{"id":1220482,"name":"Mahesh Sundararajan","orcid":"0000-0002-1522-124X","position":2,"is_corresponding":false},{"id":676638,"name":"Yong‐Min Lee","orcid":"0000-0002-5553-1453","position":3,"is_corresponding":false},{"id":676637,"name":"Mi Sook Seo","orcid":"0000-0003-3302-2508","position":4,"is_corresponding":false},{"id":1394111,"name":"Dae Young Bae","orcid":"0000-0003-0593-3064","position":5,"is_corresponding":false},{"id":1394112,"name":"Xiaoyan Lu","orcid":"0000-0001-5710-4968","position":6,"is_corresponding":false},{"id":362848,"name":"Britt Hedman","orcid":null,"position":7,"is_corresponding":false},{"id":361415,"name":"Keith O. Hodgson","orcid":"0000-0003-3059-8931","position":8,"is_corresponding":false},{"id":1394113,"name":"Won‐Suk Kim","orcid":"0000-0001-9180-4570","position":9,"is_corresponding":false},{"id":1394114,"name":"Eunsung Lee","orcid":"0000-0002-1507-098X","position":10,"is_corresponding":false},{"id":271050,"name":"Edward I. Solomon","orcid":"0000-0003-0291-3199","position":11,"is_corresponding":false},{"id":914641,"name":"Shunichi Fukuzumi","orcid":"0000-0002-3559-4107","position":12,"is_corresponding":false},{"id":676642,"name":"Wonwoo Nam","orcid":"0000-0001-8592-4867","position":13,"is_corresponding":false},{"id":1394110,"name":"Deepika G. Karmalkar","orcid":"0000-0001-7386-6989","position":0,"is_corresponding":true}],"reference_count":94,"raw_metadata":null,"created_at":"2026-07-19T02:49:54.058858Z","pmid":"39849908","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}