Genesis of electron deficient Pt1(0) in PDMS-PEG aggregates

While numerous single atoms stabilized by support surfaces have been reported, the synthesis of in-situ reduced discrete metal atoms weakly coordinated and stabilized in liquid media is a more challenging goal. We report the genesis of mononuclear electron deficient Pt₁(0) by reducing H₂PtCl₆ in liquid polydimethylsiloxane-polyethylene glycol (PDMS-PEG) (Pt₁@PDMS-PEG). UV-Vis, far-IR, and X-ray photoelectron spectroscopies evidence the reduction of H₂PtCl₆. CO infrared, and ¹⁹⁵Pt and ¹³C NMR spectroscopies provide strong evidence of Pt₁(0), existing as a pseudo-octahedral structure of (R¹OR²)₂Pt(0)Cl₂H₂ (R¹ and R² are H, C, or Si groups accordingly). The weakly coordinated (R¹OR²)₂Pt(0)Cl₂H₂ structure and electron deficient Pt₁(0) have been validated by comparing experimental and DFT calculated ¹⁹⁵Pt NMR spectra. The H⁺ in protic state and the Cl^- together resemble HCl as the weak coordination. Neutralization by a base causes the formation of Pt nanoparticles. The Pt₁@PDMS-PEG shows ultrahigh activity in olefin hydrosilylation with excellent terminal adducts selectivity.