Complexes of hydroxamates-IV. The affinity of serinehydroxamate to iron(III); equilibrium and kinetic study

The SQUAD II program has been used to determine the formation constants of the serinehydroxamate (SX^-) complexes of iron(III) at I = 0.15 M NaCl and T {reversed tilde equals} 25°C. The data were obtained from a spectrophotometric study in the wavelength range 400-600 nm and pH range 2.24-9.00. Stopped-flow kinetic data were also obtained in the wavelength range 350-480 nm (I = 0.15, T = 25°C) and the pH range 1.2-4.2. The kinetic data conformed to the equation k_{o b s} = A + B T_{S X}, where T_sx is the analytical concentration of SX and the parameters A and B are pH dependent. A mechanism was proposed to account for the kinetic result in which the species (SX^-:Fe³⁺:H⁺) 1:1:0 and 1:1:1 are the sole complexes formed.