The Front Cover shows selected tetrapodal‐pentadentate “butterflies” taking flight. First noted as bearing resemblance to butterflies by Paine and Nordlander, these 5‐coordinate frameworks have found applications in areas such as H2 evolution catalysis, N2 reduction chemistry, and as scaffolds to support high‐valent metal‐oxo compounds. Our contribution to this topology consists of a carbon butterfly composed of five N‐heterocyclic carbene donors bridged by arylborate linkers to provide a dianionic framework upon removal of five protons. More information can be found in the Research Article by J. J. Scepaniak and co‐workers.
We report the first tetrapodal pentadentate ligand composed of five N‐heterocyclic carbene donors. The proto‐ligand [CC4H5Me](OTf)3 (3) is formed in good yields from commercially available reagents. Upon removal of 5 proton equivalents from 3 with bulky non‐nucleophilic bases a dianionic penta‐carbene framework is provided in good yields as a dilithium complex CC4MeLi2 (4). Addition of FeCl3 to a solution of 4 formed in situ provides CC4MeFeCl (5) in moderate yield. Solution‐state magnetism measurements of 5 are consistent with a S=1/2 Fe(III) center. The related diamagnetic Fe(II) compound CC4MeFe (6) can be formed through reduction of 5 using KC8 though poor solubility characteristics have hampered its formation on a preparative scale and full characterization.
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