All chemicals were purchased from Sigma Aldrich. A solution of 50 mM disodium acetylene dicarboxylate, 100 mM sodium sulphite and 7 mM ruthenium catalyst [RuCp*(CH3CN)3]PF6 in D2O was prepared by dissolving the solids by heating and sonication. The sodium sulphite was added to increase the rate of reaction as discussed in Ref. .