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

Substitution reactions of the complex ions [RuIIX bipy trpy]+ and [RuIIX2 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 pKa values of the aquo complexes are shown to be 10.0 for [RuII(H2O) bipy trpy]2+ and about 9-10 for [RuII(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.