Tanaka Y, Kawano R, Akita M. Acene Size-Dependent Transition of The Radical Centers From the Metal to The Acene Parts In Monocationic Dinuclear (Diethynylacene)diyl Complexes.
Chemistry 2022;
28:e202201358. [PMID:
35680560 PMCID:
PMC9804824 DOI:
10.1002/chem.202201358]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Indexed: 01/09/2023]
Abstract
Controlling radical localization/delocalization is important for functional materials. The present paper describes synthesis and results of electrochemical, spectroscopic, and theoretical studies of diruthenium (p-diethynylacene)diyl complexes, Me3 Si-(C≡C)2 -Ru(dppe)2 -C≡C-Ar-C≡C-Ru(dppe)2 -(C≡C)2 -SiMe3 (1-6) (dppe: 1,2-bis(diphenylphosphino)ethane), and their monocationic radical species ([1]+ -[6]+ ). The HOMO-LUMO energy gaps can be finely tuned by the acene rings in the bridging ligands installed, as indicated by the absorption maxima of the electronic spectra of 1-6 ranging from the UV region even to the NIR region. The cationic species [1]+ -[6]+ show two characteristic NIR bands, which are ascribed to the charge resonance (CR) and π-π* transition bands, as revealed by spectroelectrochemistry. Expansion of the acene rings in [1]+ -[6]+ causes (1) blue shifts of the CR bands and red shifts of the π-π* transition bands and (2) charge localization on the acene parts as evidenced by the ESR, DFT and TD-DFT analyses. Notably, the monocationic complexes of the larger acene derivatives are characterized as the non-classical acene-localized radicals.
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