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While ZrO2 is known to have a large effect on the activity and selectivity of the Cu/ZrO2 catalyst for methanol synthesis, its role in this process is poorly understood. Surface defects such as oxygen vacancies could play a role in the strong metal‐support interaction (SMSI) between Cu and ZrO2. However, due to the complexity of the surfaces, the exact molecular nature of this interaction is not at present known. Here, we make well‐defined models of both reduced and coordinatively unsaturated surface oxygen vacancies on ZrO2 using the molecular precursor [Cp2ZrCl]2(μ2‐O) (1). Complex 1 can be reduced to form a complex (2) containing one Zr(III) center and a bridging hydride ligand (according to EPR and IR spectroscopy) derived from C−H activation of either thf or the Cp ring. Complex 2 reacts with CO2 to largely produce CO, suggesting that surface defects with similar structures probably do not play a role in the industrial catalyst. Halide abstraction from complex 1 results in the Lewis acidic species 3, which has similar Lewis acid properties to acidic defects on the ZrO2 surface. Similarities of both of these model species to real surface oxygen vacancies and their role in the catalytic reaction are discussed. [ABSTRACT FROM AUTHOR]

While ZrO2 is known to have a large effect on the activity and selectivity of the Cu/ZrO2 catalyst for methanol synthesis, its role in this process is poorly understood. Surface defects such as oxygen vacancies could play a role in the strong metal‐support interaction (SMSI) between Cu and ZrO2. However, due to the complexity of the surfaces, the exact molecular nature of this interaction is not at present known. Here, we make well‐defined models of both reduced and coordinatively unsaturated surface oxygen vacancies on ZrO2 using the molecular precursor [Cp2ZrCl]2(μ2‐O) (1). Complex 1 can be reduced to form a complex (2) containing one Zr(III) center and a bridging hydride ligand (according to EPR and IR spectroscopy) derived from C−H activation of either thf or the Cp ring. Complex 2 reacts with CO2 to largely produce CO, suggesting that surface defects with similar structures probably do not play a role in the industrial catalyst. Halide abstraction from complex 1 results in the Lewis acidic species 3, which has similar Lewis acid properties to acidic defects on the ZrO2 surface. Similarities of both of these model species to real surface oxygen vacancies and their role in the catalytic reaction are discussed. [ABSTRACT FROM AUTHOR]

Supported single-site platinum hydride compounds are promising heterogeneous catalysts for organic transformations. Few methods exist to describe the structures of single-site Pt catalysts with atomic resolution because of their disordered structures and low Pt loadings. Here, we study the compounds formed when bis(tri- tert -butylphosphino)platinum, Pt(P t Bu 3 ) 2 , is supported on dehydroxylated SiO 2 or SiO 2 -Al 2 O 3 . First, we obtain magic angle spinning (MAS) 1 H, 31 P and 195 Pt ssNMR spectra of four model Pt phosphine compounds with oxidation states of 0 or +2 and coordination numbers between 2 and 4. These compounds are analogs of potential structures present in the supported compounds. MAS 195 Pt ssNMR spectra were obtained using 31 P{ 195 Pt} sideband selective J -resolved and J -HMQC experiments. The measured 1 H and 31 P chemical shifts, 31 P- 195 Pt J -couplings and 195 Pt chemical shift (CS) tensors are shown to be diagnostic of oxidation state and coordination number. Room temperature 1 H ssNMR spectra of Pt(P t Bu 3 ) 2 supported on SiO 2 or SiO 2 -Al 2 O 3 show diagnostic hydride NMR signals, suggesting that Pt(P t Bu 3 ) 2 undergoes oxidative addition, resulting in surface hydrides and Pt-oxygen bonds to the support surface. MAS dynamic nuclear polarization (DNP) enables 31 P{ 195 Pt} correlation NMR experiments on the supported compounds. These experiments enable the measurement of the 31 P- 195 Pt J -coupling constants and 195 Pt CS tensors. Combined NMR and DFT analyses suggest that the primary surface platinum species are [HPt(P t Bu 3 ) 2 OSi] on SiO 2 and [HPt(P t Bu 3 ) 2 ] + [Si-O - -Al] on SiO 2 -Al 2 O 3 . The Pt-oxygen bond length is dependent on the support and estimated as 2.1-2.3 Å and 2.7-3.0 Å for SiO 2 and SiO 2 -Al 2 O 3 , respectively., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)