Scheme 3. Irradiation of a mixture of complex 1 (125 μM) and the photoacid PAH (8 equiv.) in CD₃CN/D₂O (8 : 2) by violet light results in the displacement of the pyridyl ligands as evidenced by the ¹H NMR (left side) and ³¹P NMR spectra (right side). The triflate anions of 1 are not shown for clarity. L indicates solvent or OTf^–.