Proc. Indian Acad. Sci. (Chem. Sci.), Vol. 106, No. 3, Jurie 1994, p. 809. �9 Printed in India.

Kinetics of electron transfer between nickel (IV) oxime-imine complexes and sulphur(IV) in aqueous media

SANTANU BHATTACHARYA*, MAHAMMAD ALI and PRADYOT BANERJEE Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Calcutta 700032, India

The kinetics Of electron transfer between sulphur(IV) and two nickel(IV) oxime-imine complexes, [NiW(L3)z]2+ and [NiW(L2)] z+ have been investigated over a range pH 2"0-8.0. The reactions are first-order with respect to both the oxidants and S ~lv~. A single step 2e- transfer in the region 2 ~< pH/> 5.75 for [NilV(L3)2]2+ reduction and 2 ~< 4.25 for [Ni~V(L2)] 2§ reduction has been observed. Beyond the above regions of pH, two successive le- transfer steps with the faster conversion of Ni ~v)) ~ N i m followed by a relatively slower Ni m ~ Ni u are operative. The kinetic parameters have been computed considering various protic equilibria and reaction pathways.

R,,~ NOH

R" '~Nk._../NH2

( HL ~ )

R : CH 3

RyNOH HON~ R

R N~N~__~N~___~N " "R

(H2 L2 )

* For correspondence

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