STEPWISE HYDROLYSIS KINETICS OF TETRACHLOROPLATINATE(II) IN BASE

The stepwise hydrolysis of tetrachloroplatinate(II) in basic solution is investigated by 195Pt NMR spectroscopy. Four sequential reactions are observed when 0.05 M PtCl42- is reacted with 1.0 M NaOH: [formula omitted] The reactions are not reversible, and the individual pseudo-first-order rate constants (s-1, 25 °C, μ = 1.15 M) are as follows: k1 = 6.6 × 10-5, k2 = 8 × 10-5, k} = 3.3 × 10-6, kt = 2.2 × 10-6. The hydroxide ion concentration dependence for the first reaction, corrected to μ = 0.50 M, gives [formula omitted], where [formula omitted] is 3.6 × 10-5 s-1 and k1OH is 3.7 × 10-5 M-1 s-1. The UV-vis spectrum of each Pt(II) species is resolved from repetitive scans on the basis of the NMR-determined rate constants. Dissolved O2 (1 atm pressure) in 0.8 M OH- converts Pt(OH)42- to Pt(OH)62- with a pseudo-first-order rate constant of 3 × 10-5 s-1. © 1990, American Chemical Society. All rights reserved.