Aquation of the anticancer complex trans-[RuCl4(Him)2]–(Him = imidazole)
- 1 January 1994
- journal article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 22,p. 3305-3310
- https://doi.org/10.1039/dt9940003305
Abstract
Aquation of the anticancer complex trans-[H2im][RuCl4(Him)2]1(Him = imidazole) has been studied in D2O at a range of pH*(meter reading) values between 2.4 and 10 by observation of paramagnetically shifted 1H NMR resonances. At 310 K. pH* 5.6, the half-life was 3.4 h and three products were detected, assigned as mono- and di-aqua species. The rate was similar at low pH*, but the reaction followed a different course at high pH*. Aquation was also studied by separation of the products on a reversed-phase column using HPLC, by conductivity measurements, and by EPR spectroscopy. Slow oxidation of the complex to RuIV appeared to take place in perchlorate, phosphate or acetate solutions. Cyclic voltammetric studies showed that reduction of 1 to RuII(Em–0.14 V versus the normal hydrogen electrode, pH 7) was accompanied by the uptake of two protons with associated pKa values of 6.26 and 3.87. Both aquation and the more favourable reduction of 1 at low pH may play a role in the biological activity of the complex.Keywords
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