Structural investigations of copper(II) complexes containing fluorine-substituted β-diketonate ligands

Abstract The crystal structures of the β-diketonate complexes Cu(pta) 2 , Cu(pta) 2 ·EtOH, and Cu( F 6 -thd) 2 (where pta is the anion of 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dione and F 6 -thd is the anion of 2,2-bis(trifluoromethyl)-6,6-dimethylheptane-3,5-dione) were determined. The solid-state structures of Cu(pta) 2 and Cu( F 6 -thd) 2 are square planar, while Cu(pta) 2 ·EtOH is approximately square pyramidal with the EtOH ligand occupying the apical position. In each case, only one geometrical isomer ( cis or trans ) was observed in the crystals; arguments are presented that both isomers are present in bulk samples. Calculations of molecular volumes for structurally related Cu(II) complexes containing non-fluorinated versus fluorinated ancillary ligands show that fluorine substitution does not significantly affect packing efficiency in the solid-state; however, solvent coordination decreases packing efficiency slightly. [Cu(tdf)(py)(μ-C 3 F 7 CO 2 )] 2 (where tdf is the anion of 1,1,1,2,2,3,3,7,7,8,8,9,9,9-tetradecafluorononane-4,6-dionate), a derived impurity from preparations of Cu(tdf) 2 , was isolated in low yield. The copper coordination geometries in the centrosymmetric structure are intermediate between square pyramidal and trigonal bipyramidal, with two unsymmetrically bridging μ,η 1 :η 1 -C 3 F 7 CO 2 ligands.