Transition-metal complexes with dehydroacetic acid: Crystal structure of bis(3 - acetyl - 4 - hydroxy - 6 - methyl - 2 - pyrone)cobalt(II) bis(dimethylformamide)

Co(II), Ni(II), Cu(II) and Cr(III) complexes with monoprotic dehydroacetic acid (3 - acetyl - 4 - hydroxy - 6 - methyl - 2 - pyrone) are described. The Co, Ni and Cu compounds present 1 : 2 metal: ligand ratios and the Cr compound a 1 : 3 ratio. All of these compounds are soluble in dimethylformamide and formed adducts with this solvent. One of these solvates, bis(3 - acetyl - 4 - hydroxy - 6 - methyl - 2 - pyrone)cobalt(II) bis(dimethylformamide), afforded crystals suitable for X-ray diffraction analysis, and its crystalline and molecular structures are reported. The crystals are triclinic, space group P1̄, with a = 8.290(1), b = 9.570(2), c = 7.731(1) Å, α = 94.16(2), β = 101.52(2), γ = 85.15(2)°, V = 597.9(2) Å3, Z = 1. Least-squares refinement of the structure based on 3088 observations led to final discrepancy indices of R = 0.075 and Rw = 0.049. The Co atoms lies on a inversion center having distorted octahedral coordination through four O atoms of two 3 - acetyl - 4 - hydroxy - 6 - methyl - 2 - pyrone groups and two O atoms of two dimethylformamide molecules. The 3 - acetyl - 4 - hydroxy - 6 - methyl - 2 - pyrone group is practically planar. © 1987.