Facile intramolecular silicon–carbon bond activation at Pt0 and PtII centers

The compound (2-Cy2PC6H4)2SiMe2 (1) reacted readily with Pt(PPh3)4 to undergo Si–C(sp3) bond cleavage and form the PtII species (Cy-PSiP)PtMe (2, Cy-PSiP = κ3-(2-Cy2PC6H4)2SiMe−). The silane 1 also undergoes Si–C(sp3) bond activation with the PtII precursor [(Me2S)PtMe2]2 to generate 2. Two intermediate species were observed in situ during the reaction of 1 with [(Me2S)PtMe2]2. One intermediate was tentatively assigned as the bis(phosphino) PtII species (κ2-Cy-PSiP)PtMe2 (4), which was crystallographically characterized. A second intermediate (5) was tentatively assigned as the PtIV species (Cy-PSiP)PtMe3 resulting from Si–C(sp3) bond cleavage in 4. In an effort to prepare a (Cy-PSiP)PtIV species that may serve as a model for 5, complex 2 was reacted with MeI and I2, respectively; both reactions resulted in the quantitative formation of (Cy-PSiP)PtI (6), which could also be independently prepared by the reaction of (COD)PtI2 with (Cy-PSiP)H. The reaction of (Cy-PSiP)H with PtMe3I resulted in the formation of a PtIV species (7) as the major product. Complex 7 was tentatively assigned as (Cy-PSiP)PtMe2I, and undergoes relatively facile elimination of ethane to form 6.

Two rare examples of Si–C(sp3) bond activation involving Pt are reported. The silane (2-Cy2PC6H4)2SiMe2 reacted with both Pt0 and PtII precursors to generate the PtII pincer complex (Cy-PSiP)PtMe (Cy-PSiP = κ3-(2-Cy2PC6H4)2SiMe−). This reactivity stands in contrast to Si–C(sp2) bond cleavage observed in an analogous Pd system.Figure optionsDownload as PowerPoint slide