Complexes of 2,6-diacetylpyridine dioxime (dapdoH2). Crystal structures of [M(dapdoH2)2](ClO4)2 (M = Cu and Mn)

The family of compounds M(dapdoH₂)₂](ClO₄)₂ (dapdoH₂ = diacetylpyridine dioxime; M = Mn, Co, Fe, Ni, Cu and Zn) were prepared and their properties studied and compared with the literature. The X-ray crystal structures of Mn(dapdoH₂)₂](ClO₄)₂, (1), and Cu(dapdoH₂)₂](ClO₄)₂, (5), are reported. Both exhibit the expected coordination sphere with six nitrogen atoms coordinated to the central metal, but each shows deformation from pseudo-octahedral geometry. In the case of (1), this takes the form of a significant tilting of one ligand, while in (5) the ligands are twisted toward each other, reducing the dihedral angle between them to 72°. In both cases, hydrogen bonding between the perchlorate ions and the oxime O–H groups links the units into chains. Attempts to prepare and crystallize the corresponding anions led to isolation of the oxidized products.