Cyclometalated Platinum(II) Complexes Simultaneously Catalyze the Cross-Linking of Polysiloxanes and Function as Luminophores

A family of the C,N-cyclometalated species [Pt­(ppy)­Cl­(PPh3)], [Pt­(ppy)­Cl­(CNCy)], [Pt­(ppy)­(CNCy)­(PPh3)]­(OTf), and [Pt­(ppy)­(CNCy)2]­(BF4) (ppy = 2-phenylpyridinato-C2,N; Cy = cyclohexyl) was generated from [Pt­(ppy)­(μ-Cl)]2, CNCy, and PPh3. The obtained platinum­(II) complexes were characterized by high-resolution ESI+-MS, IR, and 1D (1H, 13C­{1H}, 195Pt­{1H}) and 2D (1H,1H-NOESY; 1H,13C-HSQC; 1H,13C-HMBC) NMR spectroscopy, and the latter three complexes were investigated by X-ray diffraction. All four platinum species were examined as hydrosilylation catalysts (c 10–4–10–3 M; 80–120 °C; [Pt­(ppy)­Cl­(PPh3)] exhibited the highest catalytic activity) for the cross-linking of vinyl-terminated polydimethylsiloxane and polymethylhydrosiloxane to achieve luminescent silicone rubbers. Each solid complex and the appropriate silicone rubber exhibited the same emission spectra in the green region and strong phosphorescence with a solid-state quantum yield of up to 12.5% (measured for the silicone elastomer obtained with the [Pt­(ppy)­(CNCy)2]­(BF4) catalyst). The resulting luminescent silicone rubbers can be potentially used for protective coatings (to facilitate the thickness control) and as a component for phosphor-converted white light-emitting diodes (to transform a UV part of the LED emission to the visible spectrum).