Cobalt in a bis-β-diketiminate environment.

The reaction of Co(2)(mesityl)(4) with acetonitrile leads to the formation of a planar, low spin, bis-β-diketiminate cobalt(II) complex, (1-mesitylbutane-1,3-diimine)(2)Co (1). EPR spectroscopy, magnetic studies, and DFT calculations reveal the Co(II) ion to reside in a tetragonal ligand field with a (2)B(2)(d(yz))(1) ground state electronic configuration. Oxidation of 1 with ferrocenium hexafluorophosphate furnishes (1-mesitylbutane-1,3-diimine)(2)Co(THF)(2)PF(6) (2). The absence of significant changes in the metal-ligand bond metrics of the X-ray crystal structures of 1 and 2 supports ligand participation in the oxidation event. Moreover, no significant changes in C-C or C-N bond lengths are observed by X-ray crystallography upon oxidation of a β-diketiminate ligand, in contrast to typical redox noninnocent ligand platforms.