{"doi":"10.1021/jacs.3c10694","title":"NMR and Mössbauer Studies Reveal a Temperature-Dependent Switch from <i>S</i> = 1 to 2 in a Nonheme Oxoiron(IV) Complex with Faster C–H Bond Cleavage Rates","abstract":"S = 2 Fe IV ═O centers generated in the active sites of nonheme iron oxygenases cleave substrate C–H bonds at rates significantly faster than most known synthetic Fe IV ═O complexes. Unlike the majority of the latter, which are S = 1 complexes, [Fe IV (O)(tris(2-quinolylmethyl)amine)(MeCN)] 2+ ( 3 ) is a rare example of a synthetic S = 2 Fe IV ═O complex that cleaves C–H bonds 1000-fold faster than the related [Fe IV (O)(tris(pyridyl-2-methyl)amine)(MeCN)] 2+ complex ( 0 ). To rationalize this significant difference, a systematic comparison of properties has been carried out on 0 and 3 as well as related complexes 1 and 2 with mixed pyridine (Py)/quinoline (Q) ligation. Interestingly, 2 with a 2-Q-1-Py donor combination cleaves C–H bonds at 233 K with rates approaching those of 3, even though Mössbauer analysis reveals 2 to be S = 1 at 4 K. At 233 K however, 2 becomes S = 2, as shown by its 1 H NMR spectrum. These results demonstrate a unique temperature-dependent spin-state transition from triplet to quintet in oxoiron(IV) chemistry that gives rise to the high C–H bond cleaving reactivity observed for 2 .","journal":"Journal of the American Chemical Society","year":2024,"id":439660,"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":9,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9483,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1250981,"name":"Nabhendu Pal","orcid":"0000-0002-5559-1122","position":1,"is_corresponding":false},{"id":1250982,"name":"Ahmed M. Aboelenen","orcid":"0000-0002-7880-0660","position":2,"is_corresponding":false},{"id":1250983,"name":"Saikat Banerjee","orcid":"0000-0003-0013-8037","position":3,"is_corresponding":false},{"id":1251402,"name":"Williamson N. Oloo","orcid":null,"position":4,"is_corresponding":false},{"id":1129500,"name":"Johannes E. M. N. Klein","orcid":"0000-0002-1290-597X","position":5,"is_corresponding":false},{"id":790998,"name":"Ruixi Fan","orcid":"0000-0002-6996-4276","position":6,"is_corresponding":false},{"id":1061763,"name":"Jin Xiong","orcid":"0000-0001-7443-0554","position":7,"is_corresponding":false},{"id":777300,"name":"Yisong Guo","orcid":"0000-0002-4132-3565","position":8,"is_corresponding":false},{"id":514407,"name":"Lawrence Que","orcid":"0000-0002-0989-2813","position":9,"is_corresponding":false},{"id":1250980,"name":"Waqas Rasheed","orcid":"0000-0003-3353-9347","position":0,"is_corresponding":true}],"reference_count":38,"raw_metadata":null,"created_at":"2026-07-19T02:00:52.633010Z","pmid":"38299607","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":[]}