Oxidation induced by the antioxidant glutathione (GSH)

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1 xidation induced by the antioxidant glutathione (G) olm Petzold and Peter J. adler* Electronic supplementary information Details of NMR-experiments chemes and 2 Figure xidation of [(η 6 -MB)Ru(en)(-iPr)] + (a) using G/air, maximum efficiency of oxygen transfer Figure 2 xidation using GG/air Figure 3 Competitive oxidation of [(η 6 -MB)Ru(en)(-iPr)] + (a) and G with 2 2 Figure 4 xidation of [(η 6 -p-cymene)ru(en)(-ph)] + (b) with G/air

2 xidation reactions G in aqueous solution at p ca. 7 undergoes very slow oxidation to GG. 6 n their own in aqueous solution, complexes a and b are stable, even on bubbling with air or oxygen for several hours. In contrast, these complexes are readily oxidized to sulfenates within a few hours ( - 4 h) when G is present in solution at the same time; the G is oxidized to GG and the reactions are accelerated by bubbling with air. The reactions can be readily followed by NMR spectroscopy, but not monitored whilst bubbling with air. Longer reaction times lead to a displacement of the en ligand, probably by G or GG, and to subsequent decomposition of a and b. 0 Details of NMR-Experiments NMR spectra were recorded on a Bruker ava600 spectrometer equipped with a triple resonance TXI (, 3 C, 5 N) z-gradient cryo-probe or room temperature TXI (, 3 C, 5 N) triple-axis (x,y,z) gradient probehead. pectra were recorded at 298 K, unless otherwise stated. uppression of the water signal for 90% 2 / 0% D 2 samples was achieved by presaturation or a double-pulsed field-gradient spin-echo routine (DPFGE). 24 NMR spectra were referenced to dioxane as internal standard (3.7 ppm) N chemical shifts were referenced to N 4 as external standard. [] N N N G GG cheme : The characteristic β-c 2 NMR resonances of the thiol/disulfide used to assign the redoxstate of G/GG. For reported assignments see references

3 M C 3 [] M C 3 C 3 C 3 a 2a M [] M b 2b cheme 2: Protons (green and orange) whose NMR resonances were used to monitor the thiolato complexes a, b and sulfenato complexes 2a, 2b during the oxidation reactions. 0

4 xidation of [(η 6 -MB)Ru(en)(-iPr)] + (a) using G/air, maximum efficiency of oxygen transfer. c) b) a) δ() δ() Figure : tacked plot of -NMR spectra for a solution of complex a (0.5 mm) and G (2.5 mm). a) After mixing, and b) after bubbling air for 4 h, and c) after additional bubbling with air overnight. After the complete oxidation of G, most of the complex is oxidized to the sulfenato complex [(η 6 -MB)Ru(en)(()-iPr)] + 2a together with a small amount of decomposition of products from the starting material. Note that for every transferred oxygen atom, two molecules of G are oxidized to one molecule of GG and one water molecule is formed; therefore oxygen transfer is remarkably efficient, ca 35% of the theoretical value. For assignments see chemes and 2 (colour code: a, 2a, G, GG). xidation using GG/air a) b) δ() δ() Figure 2: When air was bubbled through a solution of complex a (0.5mM) and GG (.25 mm), no oxidation to the sulfenato complex was observed; instead displacement of the en ligand occurred with subsequent formation of various unidentified complexes. For assignments see chemes and 2 (colour code: a, 2a, GG, unidentified complexes).

5 Competitive oxidation of [(η 6 -MB) R(en) (-ipr)] + (a) and G with 2 2 Figure 3: When 2 2 ( mol equiv with respect to G) is added to a solution containing G ( mm) and complex a (0.5mM), complex a reacts faster than G. For assignments see chemes and 2 (a, 2a, G, GG). xidation of [(η 6 -p-cymene) Ru(en)(-Ph)] + (b) with G/air b) a) δ() Figure 4: NMR spectra recorded during reactions of 0.5 mm complex b with 2.5 mm G with air-bubbling for 5 h. Complete oxidation of G to GG has occurred; oxidation of complex b is incomplete, but still detectable. The phenyl substituent on the thiolate in b is a weaker electron donor compared to the isopropyl group in a and together with the presence of a weaker arene donor (pcymene compared to hexamethylbenzene) accounts for the slowing down of the reaction. For assignments see chemes and 2 (b, 2b). References 24 T. L. wang and A. J. haka, J. Magn. Reson., er. A, 995, 2, E. Gottlieb, V. Kotlyar and A. Nudelman, J. rg. Chem., 997, 62, A. Corazza, I. arvey and P. J. adler, Eur. J. Biochem., 996, 236, D. R. Frasca and M. J. Clarke, J. Am. Chem. oc., 999, 2, K. K. Millis, K.. Weaver and D. L. Rabenstein, J. rg. Chem., 993, 58,