{"doi":"10.1021/jacs.4c05367","title":"Metal–Metal Redox Exchange to Produce Heterometallic Manganese–Cobalt Oxo Cubanes via a “Dangler” Intermediate","abstract":"High Resolution Image Download MS PowerPoint Slide Pendent metals bound to heterocubanes are components of well-known active sites in enzymes that mediate difficult chemical transformations. Investigations into the specific role of these metal ions, sometimes referred to as “danglers”, have been hindered by a paucity of rational synthetic routes to appropriate model structures. To generate pendent metal ions bonded to an oxo cubane through a carboxylate bridge, the cubane Co 4 (μ 3 -O) 4 (OAc) 4 ( t -Bupy) 4 (OAc = acetate, t -Bupy = 4- tert -butylpyridine) was exposed to various metal acetate complexes. Reaction with Cu(OAc) 2 gave the structurally characterized (by X-ray diffraction) dicopper dangler Cu 2 Co 4 (μ 4 -O) 2 (μ 3 -O) 2 (OAc) 6 (Cl) 2 ( t -Bupy) 4 . In contrast, the analogous reaction with Mn(OAc) 2 produced the Mn IV -containing cubane cation [MnCo 3 (μ 3 -O) 4 (OAc) 4 ( t -Bupy) 4 ] + by way of a metal–metal exchange that gives Co(OAc) 2 and [Co III (μ–OH)(OAc)] n oligomers as byproducts. Additionally, reaction of the formally Co IV cubane complex [Co 4 (μ 3 -O) 4 (OAc) 4 ( t -Bupy) 4 ][PF 6 ] with Mn(OAc) 2 gave the corresponding Mn-containing cubane in 80% yield. A mechanistic examination of the related metal–metal exchange reaction between Co 4 (μ 3 -O) 4 (OBz) 4 (py) 4 (OBz = benzoate) and [Mn(acac) 2 (py) 2 ][PF 6 ] by ultraviolet–visible (UV–vis) spectroscopy provided support for a process involving rate-determining association of the reactants and electron transfer through a μ-oxo bridge in the adduct intermediate. The rates of exchange correlate with the donor strength of the cubane pyridine and benzoate ligand substituents; more electron-donating pyridine ligands accelerate metal–metal exchange, while both electron-donating and -withdrawing benzoate ligands can accelerate exchange. These experiments suggest that the basicity of the cubane oxo ligands promotes metal–metal exchange reactivity. The redox potentials of the Mn and cubane starting materials and isotopic labeling studies suggest an inner-sphere electron-transfer mechanism in a dangler intermediate.","journal":"Journal of the American Chemical Society","year":2024,"id":465904,"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":0.9491,"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":292449,"name":"T. Don Tilley","orcid":"0000-0002-6671-9099","position":1,"is_corresponding":false},{"id":438429,"name":"T. Alexander Wheeler","orcid":"0000-0003-4294-6817","position":0,"is_corresponding":true}],"reference_count":78,"raw_metadata":null,"created_at":"2026-07-19T02:04:50.328230Z","pmid":"38978206","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":[]}