Cobalt(III) Dimethylglyoximates Containing Selenourea and an Unusual Diselenourea Ligand: Synthesis and Structures

The complexes [Co(DH)(2)(Seu)(y)(Se-Seu)(z)](2)X center dot mSolv (DH is the dimethylglyoxime monoanion, Seu is selenourea, and X is [TiF6](2-), [ZrF6](2-)) were obtained from the system CoX center dot 6H(2)O-DH2-Seu in DMF-MeOH or MeOH-H2O and examined by UV, IR, and NMR spectroscopy and X-ray diffraction. Unexpectedly, the ligand Se-Seu (the oxidized form of selenourea) was detected on the axial coordinate, partially replacing selenourea. The complexes were formulated as [Co(DH)(2)(Seu)(1.75)(Se-Seu)(0.25)](2)[TiF6] center dot H2O (I) and [Co(DH)(2)(Seu)(Se-Seu)](2)[ZrF6] center dot 3H(2)O (II). The complex cations in I and II have trans-octahedral structures. Their crystal structures are made up of the complex Co3+ cations and the outer-sphere MF62- anions (M = Ti(IV) (I) and Zr(IV) (II)) held together by electrostatic interactions and hydrogen bonds; water of crystallization is also involved in hydrogen bonding.