CROWN THIOETHER CHEMISTRY. SYNTHETIC, STRUCTURAL, AND PHYSICAL STUDIES OF THE Cu(II) AND Cu(I) COMPLEXES OF HEXATHIA-18-CROWN-6

Article abstract of DOI:10.1021/ja00266a014

The copper(II) and copper(I) complexes of hexathia-18-crown-6 have been synthesized and characterized by electron paramagnetic resonance, electrochemical, and X-ray diffraction methods.The copper(II) complex, (picrate)2, crystallizes in the triclinic system, space group P1/, with a = 6.661(1) Angstroem, b = 9.669(2) Angstroem, and c = 13.594(3) Angstroem, α = 84.84(2)deg, β = 75.52(2)deg, and γ = 76.80(2)deg, and Z = 1.The copper(i) complex, (BF4), crystallizes in the orthorhombic system, space group Pna2₁, with a = 10.855(4) Angstroem, b = 18.592(7) Angstroem, c = 10.137(4) Angstroem, and Z = 4.The centrosymmetric copper(II) complex adopts an axially elongated octahedral geometry, with Cu-S(eq) distances of 2.323(1) and 2.402(1) Angstroem and a Cu-S(ax) distance of 2.635(1) Angstroem.Glasses at 77 K of (picrate)2 in 1:1 nitromethane-toluene yield an EPR spectrum with g_x = 2.028, g_y = 2.035, and g_z = 2.119, Α_<*> = 0.0153 cm^-1, and Α_<*> ca. o.0019 cm^-1.The copper(I) complex assumes a distorted four-coordinate geometry that can be considered as derived from a linear two-coordinate complex by addition of two thioether groups; Cu-S distances are 2.253(2) and 2.245(2) and 2.358(2) and 2.360(2) Angstroem, repectively, for these two types of ligands.Cyclic voltammetry shows that the Cu(II) and Cu(I) complexes are connected by an essentially reversible one-electron redox process at very high potential: +0.96 V vs.NHE.