Substitution reactions of some Bis(2,2'-bipyridine) and mixed 2,2'-bipyridine, 2,2',2'-terpyridine complexes of ruthenium(II)

Abstract

Substitution reactions of the complex ions [Ru^IIX bipy trpy]⁺ and [Ru^IIX₂ bipy₂]⁰, where X = Cl, Br, I; bipy = 2,2?-bipyridine; trpy = 2,2?2?- terpyridine, take place in aqueous solution via extremely rapid formation of the aquoammines. The rates of substitution of the aquo groups by NO^-₂ and N^-₃ occur by measurably slow processes at room temperature and are not base catalysed. The aquo complexes are immediately converted by OH^- into hydroxo complexes. The pK_a values of the aquo complexes are shown to be 10.0 for [Ru^II(H₂O) bipy trpy]²⁺ and about 9-10 for [Ru^II(H₂O)₂ bipy₂]²⁺, the latter being an estimate since oxidation to ruthenium(III) in alkaline solution could not be avoided. The visible and ultraviolet spectra are reported.