Addition of the Lewis acid Zn2+ to (TBP(8)Cz)Mn-V(O) induces valence tautomerization, resulting in the formation of [(TBP(8)Cz(+center dot))Mn-IV(O)-Zn2+]. This new species was characterized by UV-vis, EPR, the Evans method, and H-1 NMR and supported by DFT calculations. Removal of Zn2+ quantitatively restores the starting material. Electron-transfer and hydrogen-atom-transfer reactions are strongly influenced by the presence of Zn2+.