4,5-diazafluorene (daf) and 9,9’-dimethyl-4,5-diazafluorene (Me
2daf) 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
2daf as a ligand than those containing bpy. New complexes
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4,5-diazafluorene (daf) and 9,9’-dimethyl-4,5-diazafluorene (Me
2daf) 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
2daf as a ligand than those containing bpy. New complexes Mn(CO)
3Br(daf) (
2), Mn(CO)
3Br(Me
2daf) (
3), and [Ru(Me
2daf)
3](PF
6)
2 (
5) have been prepared and fully characterized to understand the influence of the Me
2daf 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 Me
2daf 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, Me
2daf, 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 Me
2daf 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 Me
2daf 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.
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