Synthesis and characterization of zirconium pentafluorophenyl complexes: X-ray crystal structures of [ZrCl₂(C₆F₅)₄^2-] and [ZrF₂(C₆F₅)₅^3-]

Treatment of ZrCl₄ with LiC₆F₅, followed by addition of 1,4,7,10-tetraoxacyclododecane (12-crown-4) or N,N,N′,N′-tetramethylethylenediamine (tmed), leads to the isolation of two pentafluorophenylzirconate complexes: [Li(12-crown-4)₂]₂[ZrCl₂(C₆F ₅)₄] (1) and [Li(tmed)₂][Li(tmed)]₂[ZrF₂(C₆F ₅)₅] (2). The presence of Zr-F groups in the latter compound shows that C-F bond activation has occurred. The anion in the former complex adopts an octahedral structure owing to the π-donor character of the chloride ligands, whereas the anion in the latter adopts a regular pentagonal bipyramidal structure. The lithium atoms in 1 are not interacting with the anion, whereas two of the lithium atoms in 2 are involved in LiF interactions with fluorine atoms in the anion. Selected bond distances and angles for 1: Zr-C=2.478(5)-2.510(5), Zr-Cl=2.409(5), 2.435(5) Å, C-Zr-C(cis)=77.9-106.9(2), C-Zr-C(trans)=161.1, 169.1(2), Cl-Zr-Cl=166.7(2)°. Selected bond distances and angles for 2: Zr-C=2.432-2.449(8), Zr-F=1.986(4), LiF=1.73(2)-2.50(2) Å, C-Zr-C(cis)=69.6-73.3, F-Zr-F=178.8(2)°. Crystal data for 1: monoclinic, space group P2₁/n, a=15.2288(14), b=17.328(2), c=24.013(2) Å, β=91.936(3)°, V=6333(1) ų, Z=4, wR₂=0.2985 for 7801 reflections and 722 parameters. Crystal data for 2: monoclinic, space group P2₁/n, a=11.6143(5), b=29.6561(9), c=20.4427(8) Å, β=103.266(1)°, V=6853.3(4) ų, Z=4, wR₂=0.1822 for 8762 reflections and 759 parameters.