Henke, Wade C.Hopkins, Julie A.Anderson, Micah L.Stiel, Jonah P.Day, Victor W.Blakemore, James D.2020-11-112020-11-112020-07-13Henke, W. C., Hopkins, J. A., Anderson, M. L., Stiel, J. P., Day, V. W., & Blakemore, J. D. (2020). 4,5-Diazafluorene and 9,9'-Dimethyl-4,5-Diazafluorene as Ligands Supporting Redox-Active Mn and Ru Complexes. Molecules (Basel, Switzerland), 25(14), 3189. https://doi.org/10.3390/molecules25143189https://hdl.handle.net/1808/30830This work is licensed under a Creative Commons Attribution 4.0 International License.4,5-diazafluorene (daf) and 9,9’-dimethyl-4,5-diazafluorene (Me2daf) are structurally similar to the important ligand 2,2’-bipyridine (bpy), but significantly less is known about the redox and spectroscopic properties of metal complexes containing Me2daf as a ligand than those containing bpy. New complexes Mn(CO)3Br(daf) (2), Mn(CO)3Br(Me2daf) (3), and [Ru(Me2daf)3](PF6)2 (5) have been prepared and fully characterized to understand the influence of the Me2daf framework on their chemical and electrochemical properties. Structural data for 2, 3, and 5 from single-crystal X-ray diffraction analysis reveal a distinctive widening of the daf and Me2daf chelate angles in comparison to the analogous Mn(CO)3(bpy)Br (1) and [Ru(bpy)3]2+ (4) complexes. Electronic absorption data for these complexes confirm the electronic similarity of daf, Me2daf, and bpy, as spectra are dominated in each case by metal-to-ligand charge transfer bands in the visible region. However, the electrochemical properties of 2, 3, and 5 reveal that the redox-active Me2daf framework in 3 and 5 undergoes reduction at a slightly more negative potential than that of bpy in 1 and 4. Taken together, the results indicate that Me2daf could be useful for preparation of a variety of new redox-active compounds, as it retains the useful redox-active nature of bpy but lacks the acidic, benzylic C–H bonds that can induce secondary reactivity in complexes bearing daf.© 2020 by the authors. Licensee MDPI, Basel, Switzerland.http://creativecommons.org/licenses/by/4.0/Manganese tricarbonylRutheniumElectrochemistry4,5-diazafluorene9,9’-dimethyl-4,5-diazafluoreneArticle10.3390/molecules25143189https://orcid.org/0000-0003-4172-7460PMC7396985openAccess