Isolation of Bis(η²-nitrato)(η⁴-cyclobutadiene)cobalt(II) Complexes from the Oxidation of Sterically Hindered CpCo-Stabilized Cyclobutadiene Complexes

The oxidation of sterically hindered, CpCo-protected cyclobutadienes with ceric ammonium nitrate (CAN) yielded the paramagnetic Co(NO₃)₂-protected cyclobutadiene products. These half-sandwich complexes represent possible intermediates within the mechanism of the CAN decomplexation of CpCo−cyclobutadiene complexes.