Crystal and molecular structure oftrans-bis-(1,1,1-trifluoro-5-methoxy-5-methyl-2,4-hexanedionato) copper(II)

A combined X-ray diffraction study of the single crystals (Enraf-Nonius CAD-4 automatic diffractometer, MoK_α radiation, graphite monochromator) and polycrystals (DRON-UM1, CuK_α radiation, Ni filter) of a new volatile complex of Cu(II) obtained from fluorinated alkoxy-Β-diketone, CF₃-CO-CH₂-CO-C(CH₃)₂OCH₃, is reported. The compound has a molecular structure; the crystals consist of trans-bis(1,1,1-trifluoro-5-methoxy-5-methyl-2,4-hexanedionato)copper(II) complexes. The structure was refined anisotropically for 2314 independent reflections with I > 2Σ(I) to R = 0.069. Crystal data: a = 24.469(3), c = 10.581(2) å, V = 5486.4 å³, space group R3, Z = 9, d_calc = 1.17 g/cm³. The complexes are packed to form through channels ≈5 å in diameter along the c axis, with terminal fluorine atoms facing the channels. The crystal-chemical data of the compound are compared with those of the nonfluorinated analog, trans-bis(2-methoxy-2,6,6-trimethylheptane-3,5-dionato)copper(II). The introduction of CF₃ groups into alkoxy-Β-diketone considerably decreases the sublimation temperature of the complex. The geometrical characteristics of chelate nodes in the complexes are almost equal: the Cu-0 distances are 1.92 å and the O-Cu-0 bond angles 92.1? (average). In both cases, the square planar environment of the Cu atom is completed to bipyramidal by interactions with the oxygen atoms of the methoxy groups of the neighboring molecules, with Cu...O distances being 2.8 å.