45-Diazafluorene and 99’-Dimethyl-45-Diazafluorene as Ligands Supporting Redox-Active Mn and Ru Complexes

摘要

4,5-diazafluorene (daf) and 9,9’-dimethyl-4,5-diazafluorene (Me daf) 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 Me daf as a ligand than those containing bpy. New complexes Mn(CO) Br(daf) ( ), Mn(CO) Br(Me daf) ( ), and [Ru(Me daf) ](PF ) ( ) have been prepared and fully characterized to understand the influence of the Me daf framework on their chemical and electrochemical properties. Structural data for , , and from single-crystal X-ray diffraction analysis reveal a distinctive widening of the daf and Me daf chelate angles in comparison to the analogous Mn(CO) (bpy)Br ( ) and [Ru(bpy) ] ( ) complexes. Electronic absorption data for these complexes confirm the electronic similarity of daf, Me daf, 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 , , and reveal that the redox-active Me daf framework in and undergoes reduction at a slightly more negative potential than that of bpy in and . Taken together, the results indicate that Me daf 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.