Fig. 4. ¹³C NMR spectra of a DMSO-d₆ solution containing TEOA (1.3 M) and the Mn complexes (1Mn-bpy and 2Mn-bpy; their total concentration was 35 mM) after bubbling with (a) CO₂ and (b) ¹³CO₂; both are proton-decoupled. (c) The spectrum without proton decoupling for the same sample as in (b).