Synthesis and characterization of Marko-type (NHC)Pt(dvtms) complexes and their evaluation in the hydrosilylation reaction of alkenes

A series of Mark ' o-type complexes of the structure (NHC)Pt(dvtms) were prepared (dvtms = 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, NHC = N-heterocyclic carbene, Im = imidazole, Trz = triazole; NHC = iPrIm (1), PhIm (2), 2-PyIm (3), MesTrzMeIm (4) Mes(Me)Trz (5) MeIm (6), MesIm(7)), with 5 being the first reported abnormal 1,2,3-triazole-5-ylidene Pt(0) complex. All these compounds are easily accessible using Karstedt's catalyst [Pt2(dvtms)3], the respective azolium salts (L1-7) and potassium tert-butoxide. Comprehensive characterization by NMR spectroscopy (1H, 13C, 29Si, 195Pt), SC-XRD and CHNS analysis is presented. The hydrosilylation re-actions of oct-1-ene or MMVi with MDHM, respectively, where the latter mimics the cross linking of silicones, are efficiently catalyzed at remarkable low Pt-loadings of 50-100 ppm.