bis-Nitrile and bis-Dialkylcyanamide Platinum(II) Complexes as Efficient Catalysts for Hydrosilylation Cross-Linking of Siloxane Polymers

cis- and trans-Isomers of the platinum(II) nitrile complexes [PtCl(2)(NCR)(2)] (R = NMe(2), N(C(5)H(10)), Ph, CH(2)Ph) were examined as catalysts for hydrosilylation cross-linking of vinyl-terminated polydimethylsiloxane and trimethylsilyl-terminated poly(dimethylsiloxane-co-ethylhydrosiloxane) producing high quality silicone rubbers. Among the tested platinum species the cis-complexes are much more active catalysts than their trans-congeners and for all studied platinum complexes cis-[PtCl(2)(NCCH(2)Ph)(2)] exhibits the best catalytic activity (room temperature, c = 1.0 × 10(−4) mol/L, τ(pot-life) 60 min, τ(curing) 6 h). Although cis-[PtCl(2)(NCCH(2)Ph)(2)] is less active than the widely used Karstedt’s catalyst, its application for the cross-linking can be performed not only at room temperature (c = 1.0 × 10(−4) mol/L), but also, more efficiently, at 80 °C (c = 1.0 × 10(−4)–1.0 × 10(−5) mol/L) and it prevents adherence of the formed silicone rubbers to equipment. The usage of the cis- and trans-[PtCl(2)(NCR)(2)] complexes as the hydrosilylation catalysts do not require any inhibitors and, moreover, the complexes and their mixtures with vinyl- and trimethylsilyl terminated polysiloxanes are shelf-stable in air. Tested catalysts do not form colloid platinum particles after the cross-linking.