Paramagnetic transition metal complexes with a redox-active ligand: M(hfac)2(EDO-EDT-TTF-py)n; [M = CuII, n = 1, 2; M = MnII, n = 2]

Abstract

Synthesis, crystal structures, electrochemical and physical properties of the new ligand, EDO-EDT-TTF-py (L1) [4,5-ethylenedioxy-4′,5′-(4-pyridylethylenedithio)tetrathiafulvalene], and the paramagnetic transition metal coordination complexes, M(hfac)₂(EDO-EDT-TTF-py)₂; M = Cu^II (2), Mn^II (3), and Cu^II(hfac)₂(EDO-EDT-TTF-py) (4) are reported where hfac = hexafluoroacetylacetonato. Crystal data: (L1) triclinic system, space group P, a = 8.4060(3), b = 10.5093(3), c = 11.5318(5) Å, α = 64.758(2), β = 86.923(2), γ = 72.444(2)°, V = 875.22(6) ų, Z = 2, 2 and 3 are isostructural (data for 3 are given in brackets), triclinic system, space group P, a = 7.1085(4) [7.1013(9)Å], b = 11.1210(7) [11.111(2)Å], c = 16.3628(11) Å [16.346(3) Å], α = 91.682(2) [91.662(6)], β = 91.014(3) [91.036(7)], γ = 93.547(3)° [93.651(6)°], V = 1290.3(1) ų [1286.3(3) ų], Z = 1, (4) triclinic system, space group P, a = 9.2937(1), b = 15.1897(2), c = 24.3174(6) Å, α = 92.461(1), β = 93.048(1), γ = 105.491(1)°, V = 3297.6(1) ų, Z = 4. In the compounds 2, 3 and 4, the ligand L1 is coordinated to the transition metals through the nitrogen atom of the pyridine group. In the crystal, the organic and inorganic layers are segregated. The arrangement of the organic layers is similar to the well known β phase in BEDT-TTF [bis(ethylenedithio)tetrathiafulvalene] charge transfer complexes, showing that the crystal packing is mainly governed by π–π stacking of the organic molecules. L1 is a TTF derivative and shows the electron donating ability with oxidation potential E₁^½ = +0.52 V versus SCE in benzonitrile. The same oxidation potentials were observed for complexes 2 and 3, indicating the negligible interactions between the ligands and the metals in solution.