biostudies-literatureRoy MDDivision of ChemistryBasic Energy SciencesAlfred P. Sloan FoundationChemical Sciences, Geosciences, and Biosciences DivisionState of FloridaDivision of Materials ResearchNational Institute of General Medical SciencesNIGMS NIH HHSLos Alamos National Laboratory5560-5568https://www.ebi.ac.uk/biostudies/studies/S-EPMC10910554biostudies-literatureUnknown146(8)There are several reports of compounds containing lanthanide ions in two different formal oxidation states; however, there are strikingly few examples of intervalence charge transfer (IVCT) transitions observed for these complexes, with those few occurrences limited to extended solids rather than molecular species. Herein, we report the synthesis, characterization, and computational analysis for a series of ytterbium complexes including a mixed-valence Yb₂⁵⁺ complex featuring a remarkably short Yb···Yb distance of 2.9507(8) Å. In contrast to recent reports of short Ln···Ln distances attributed to bonding through 5<i>d</i> orbitals, the formally Yb₂⁵⁺ complex presented here displays clear localization of Ln²⁺ and Ln³⁺ character and yet still displays an IVCT in the visible spectrum. These results demonstrate the ability to tune the electronic structure of formally mixed oxidation state lanthanide complexes: the high exchange stabilization of the Yb²⁺ 4<i>f</i>¹⁴ configuration disfavors the formation of a 5<i>d</i>¹ bonding configuration, and the short metal-metal distance enforced by the ligand framework allows for the first observed lanthanide IVCT in a molecular system.Journal of the American Chemical SocietyIntervalence Charge Transfer in Nonbonding, Mixed-Valence, Homobimetallic Ytterbium Complexes.PMC109105542020LANLE372DE-SC0019385P30GM13389489233218CNA000001DMR-1644779CHE-2246913P30 GM133894DE-SC-001866020230399ERDE-AC02-76SF00515Nassar LSStein BWLa Pierre HSGreer SMBacsa JGompa TPRoy MDJiang NSteiner AfalseIntervalence Charge Transfer in Nonbonding, Mixed-Valence, Homobimetallic Ytterbium Complexes.There are several reports of compounds containing lanthanide ions in two different formal oxidation states; however, there are strikingly few examples of intervalence charge transfer (IVCT) transitions observed for these complexes, with those few occurrences limited to extended solids rather than molecular species. Herein, we report the synthesis, characterization, and computational analysis for a series of ytterbium complexes including a mixed-valence Yb₂⁵⁺ complex featuring a remarkably short Yb···Yb distance of 2.9507(8) Å. In contrast to recent reports of short Ln···Ln distances attributed to bonding through 5<i>d</i> orbitals, the formally Yb₂⁵⁺ complex presented here displays clear localization of Ln²⁺ and Ln³⁺ character and yet still displays an IVCT in the visible spectrum. These results demonstrate the ability to tune the electronic structure of formally mixed oxidation state lanthanide complexes: the high exchange stabilization of the Yb²⁺ 4<i>f</i>¹⁴ configuration disfavors the formation of a 5<i>d</i>¹ bonding configuration, and the short metal-metal distance enforced by the ligand framework allows for the first observed lanthanide IVCT in a molecular system.2024-01-01T00:00:00Z2024 Feb2026-06-16T04:53:25.271Z2025-04-05T11:38:51.627ZS-EPMC109105543837343910.1021/jacs.3c13906