While ester hydrolysis for ethyl glycinate N-bonded to Co(NH3)53+ has a half-life in 1 M CF3SO3H at 25?C in excess of 1 month, reaction for the corresponding Ru(III) complex under the same conditions is complete in 1 h. The reaction products in the latter case are ([(NH3)5RuH2O]3+ + [C2H5O2CCH2NH3] +), 30%, and ([(NH3)5RuO2CCH2NH3] 3+ + C2H5OH), 70%. It needs to be emphasized that the facile ester hydrolysis takes place with the pentaammine unit remaining intact and does not involve replacement of NH3. The rate of consumption of the reactant increases with acid but reaches a limiting value at high acid concentration. In the saturation region, the half-life for the consumption of the reactant is 12 min. When the noncomplexing acid is replaced by HCl, [(NH3)5RuCl]2+ is formed in place of the aquo ion, but this change in stoichiometry does not affect the rate. The observations are fully accounted for by a rather facile (k1 = 1.14 ? 10-3 s-1) rearrangement of [(NH3)5RuNH2CH2CO2C 2H5]3+ to the linkage isomer [(NH3)5RuOC(OC2H5)CH 2NH2]3+. This intermediate is stabilized against reversion to the N-bound form by protonation and at 25?C undergoes competition between ester hydrolysis (70%) or aquation/anation (30%). A trace of Ru(II) leads quantitatively to the anation product; at high acid this does not affect the half-life for consumption of the N-bound ester. ? 1980 American Chemical Society.
Relation:
Journal of the American Chemical Society Volume 102, Issue 14, 1980, Pages 4725-4729
