Syntheses, Structures, and Properties of Substituted Co(C5Me5)(2,7-di(OCH3)fluorenido Co(II) and Co(III) Complexes

The title compound, η5-2,7-dimethoxyfluorenido-η5-pentamethyl­cyclopentadienyl­cobalt­(II) (1), was synthesized from Cp*Co­(acac) and sodium 2,7-dimethoxyfluorenide. 1 was oxidized with AgBF4 to yield the cobaltocenium congener 1BF4. The structural comparison of both compounds reveals structural changes in the ligand scaffold. In the electronic spectra of 1, an MLCT transition was found that could be assigned by TD-DFT calculations. In this transition a significant quantity of spin-density is transferred to the fluorenido ligand, allowing for possible spin-filter or spin-injection applications.