Abstract
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.
Highlights
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
The synthesis of discrete reduced metal atoms with weak coordination, which are sufficiently stable in storage at moderate temperature has not been reported
Ethanol is used as the reductant for Pt(IV)[17,18], in the presence of optimized 10% (v/v) water to accelerate the rate of reduction[9], while the diverse oxygen-containing functionality of PDMS-PEG offer weak coordination to the Pt atoms
Summary
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. Reduced single atoms tend to aggregate into nanoparticles in liquid media in the absence of strong ligand coordination[9]. Synthesis of weakly coordinated and yet stable metal atoms in liquid media may pave a new path for facile preparation of highly dispersed metal catalysts by overcoming the long-standing challenge of metal aggregation. The synthesis of discrete reduced metal atoms with weak coordination, which are sufficiently stable in storage at moderate temperature has not been reported. Ethanol is used as the reductant for Pt(IV)[17,18], in the presence of optimized 10% (v/v) water to accelerate the rate of reduction[9], while the diverse oxygen-containing functionality of PDMS-PEG offer weak coordination to the Pt atoms
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