Kinetics of dissociation of tris(1,10-phenanthroline)iron(II) in aqueous and reverse micellar media- catalysis of CuII, NiII and CoII ions

Department of Physical and Nuclear Chemistry, School of Chemistry, Andhra University,

Visakhapatnam-530 003, India

E-mail : p_ vsrao@hotmail.com

Manuscript received 13 December 2001, revised 3 June 2002, accepted 13 August 2002

The rate of dissociation of tris(1,10-phenanthroline)iron(ll) ([Fe(phen)3]²⁺) is markedly increased in the presence of metal ions, Cu^II, Ni^II and Co^II in the water pools of CTAB reverse micelles in chloroform-hexane mixture (3 : 2, v/v) compared to the aqueous medium. In both the media, the k'-(Metal ion]_err profiles exhibit limiting behavior at higher metal ion concentrations and the plots of 1/k' vs 1/( Metal ion]_eff are linear with positive slopes and intercepts. The kinetic results are in accord with the mechanism envisaging the formation of 1 : 1 binuclear intermediate between [Fe(phen)₃]²⁺ and metal ion following the rupture of one of the coordinate bonds of 1,10-phenanthroline aided by the nucleophilic effect of bromide ion. The catalytic effect of the metal ions in both the media is in accordance with the Irving-William series.