Linear End‐On Coordination Modes of CO2

The second case of linear end‐on and evidence for an unprecedented bridging end‐on coordination mode of CO2 have been discovered for vanadium aryloxide complexes of the tetradentate ligand system (ONNO)2− (ONNO=2,4‐Me2‐2‐(OH) C6H2CH2]2N(CH2)2NMe2). The reaction of divalent (ONNO)VII (TMEDA) with CO2 and under the appropriate reaction conditions affords the trivalent (ONNO)VIII(OH)(η1‐CO2) resulting from an intermediate CO2 deoxygenation pathway followed by H‐atom ion from the aromatic solvent, and CO2 fixation. In contrast, the reduction of trivalent (ONNO)VIIICl(THF) with K, followed by exposure to CO2 in ethereal solvent, afforded the dinuclear [(ONNO)VII]2 (μ,η1‐CO2). A happy end‐on: A new bonding mode of CO2 in vanadium complexes is reported as a starting point for radical H‐atom ion.