Polymer-supported catalysts are versatile compounds for the synthesis of different molecules.¹ Among polymers, polysiloxanes possess good film-forming abilities, flexibility, a wide range of working temperatures (from –123 to +250 °C), and UV resistivity.² These properties make them desirable candidates for catalytic application in homogeneous and heterogeneous catalysis. The functionalization of polysiloxanes with platinum-group metal complexes opens up new opportunities for usage of the resulting metal–polymer compounds for catalytic hydrosilylation and dehydrocoupling reactions for platinum-containing complexes and for carbon–carbon cross-coupling reactions for palladium-containing polysiloxanes. Considering the nature of the catalytic reactions (homogeneous or heterogeneous), homogeneous catalysts usually demonstrate high catalyst activity and a short reaction time, but they contaminate the product of the reactions with metal and do not allow for the recovery and reuse of catalysts several times. This is crucial, taking into account the high price of platinum-group metals. Alternatively, heterogeneous catalysts can be used. Despite some of its limitations such as lower reaction rates and yields, heterogeneous catalysts are easier to recover and reuse several times.³

Thus, the aim of this study is to synthesize polysiloxanes that have functionalized using platinum and palladium complexes. We synthesized platinum-functionalized polysiloxane (Pt-PDMS) via Cu(I)-catalized azide-alkyne cycloaddition between a palladium C,N-cyclometalated complex and (3-azidopropyl)polysiloxane. Its activity was investigated in Si–O dehydrocoupling reactions⁴. Palladium-containing polysiloxane (Pd-PDMS) was synthesized in a similar way to the Pt-PDMS method. The catalytic activity of Pd-PDMS was examined in carbon–carbon cross-coupling reactions.³ The resulting catalysts demonstrated high catalytic activity in the performed reactions, without yield loss after several catalytic cycles. The usage of both Pt-PDMS and Pd-PDMS allows one to recover and reuse catalysts easily.

The authors acknowledge St Petersburg State University for a research project grant, with the number 95408592.

References

1. Munirathinam, R.; Huskens, J.; Verboom, W. Supported catalysis in continuous‐flow microreactors. Synth. Catal., 2015, 357(6),1093-1123.
2. Mark, J.E.; Schaefer, D.W.; Lin, G. The polysiloxanes. Oxford University Press., 2015.
3. Golovenko, E. A.; Kocheva, A. N.; Semenov, A. V.; Baykova, S. O.; Deriabin, K. V.; Baykov, S. V.; Boyarskiy, V.P.; Islamova, R. M. Palladium-functionalized polysiloxane drop-casted on carbon paper as a heterogeneous catalyst for the Suzuki–Miyaura reaction. Polymers, 2024, 16(19), 2826.
4. Deriabin, K.V.; Golovenko, E.A.; Antonov, N.S.; Baykov, S.V.; Boyarskiy, V.P.; Islamova, R.M. Platinum macrocatalyst for heterogeneous Si–O dehydrocoupling. Dalton Trans., 2024, 52(18), 5854-5858.