Kinetic Data for Outer-sphere V(2+) and (2+) Reductions of Platinum(IV) Complexes and a Correlation of Rate Constants

Article abstract of DOI:10.1039/DT9800000019

The kinetics of 2:1 V(2+) and (2+) reductions of six Pt(IV) complexes: trans-(2+), trans-(2+), (3+), (3+), mer-(3+), and (2-) have been studied.Reactions involve one-equivalent changes, Pt(IV) -> Pt(III) -> Pt(II) where the first step is rate determining and Pt(III) is a transient intermediate.A linear correlation of second-order rate constants (15 deg C) k_V and k_Ru, logk_V=0.89logk_Ru - 1.68, is obtained at l=0.10M (LiClO4), consistent with outer-sphere reactions, and non-utilization (by V(2+)) of inner-sphere pathways involving Cl(1-) and Br(1-) br idges.The occurrence of outer-sphere reactions appears to preclude two equivalent changes.Rate constants for the V(2+) reductions of trans-(2+) > (3+) differ by a factor of 60, whereas those for corresponding (2+) reductions, which involve two-equivalent changes, have previously been shown to differ by a factor 1E4.Activation parameters have been determined for five of the V(2+) reductions.Those for the reduction of trans-(2+) and trans-(2+) differ significantly indicating an influence of the methyl groups.

Full text of DOI:10.1039/DT9800000019

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