摘要:
The chemistry of the bidentate (S,S')- donor ligand 2-aminocyclopent-1-ene-1-carbodithioic acid (Hacda) and its N-alkylated derivatives [R = Et (Heacda), Pr(n) (Hpacda), or Bu(n) (Hbacda)] with vanadium(IV) and manganese(III) has been studied. The vanadium(IV) complexes [V(aacda)4] 1 a-1d are all eight-co-ordinated non-oxo species containing a VS8 chromophore. Their ESR spectra in frozen solution (140 K) exhibit axial anisotropy with a 16-line V-51 hyperfine pattern. The observed order in spin-Hamiltonian parameters (g(parallel-to) almost-equal-to 1.932, g(perpendicular-to) almost-equal-to 1.985, A(parallel-to) almost-equal-to 175 x 10(-4) cm-1 and A(perpendicular-to) almost-equal-to 74 x 10(-4) cm-1) indicates a d(x2-y2) ground state with a dodecahedral (D2d) structure. Electrochemical studies of 1a-1d show a quasi-reversible one-electron V(IV)-V(III) reduction at almost-equal-to -0.7 V vs. saturated calomel electrode (SCE). The manganese(III) complexes [Mn(aacda)3] 2a-2c are all high-spin species (mu(eff) 5.01-5.10) and exhibit two ligand-to-metal charge-transfer bands at almost-equal-to 610 and 530 nm. Their cyclic voltammograms reveal the presence of two quasi-Nernstian couples: E1/2(ox) = 0.1 V and E1/2(red) = -0.33 V vs. SCE due to Mn(IV)Mn(III) and Mn(III)-Mn(II)l electron transfers respectively.