Kinetic and mechanistic studies on the interaction of adenosine with hydroxopentaaquarhodium(III) ion

The kinetics of the title reaction have been studied spectrophotometrically as a function of pH, substrate], adenosine] and temperature (50–65°C) by monitoring the appearance of a characteristic peak of the adenosine substituted product (λ_max = 289 nm). The reaction rate is pH dependent in the 3.0–4.3 range. With increase in adenosine] the rate was found to increase and approached a limit at a higher adenosine concentration. The following rate law has been established at pH 4.3: dRh(H₂O)₃(OH)(adenosine)²⁺]/dt = k _a K _ERh(H₂O)₅(OH)²⁺]_totaladenosine]/ (1 + K _Eadenosine]) Rate and activation parameters are consistent with an associative interchange mechanism. Experimental results are discussed with reference to literature data for analogous systems. This revised version was published online in June 2006 with corrections to the Cover Date.