Effects of surface acidity on the structure of organometallics supported on oxide surfaces

Conley, Matthew P.; Samudrala, Kavyasripriya

doi:10.1039/d3cc00047h

Cited by 13 publications

(19 citation statements)

References 176 publications

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“…L n M–R + forms readily in solution or on solid supports in common industrial compositions used for ethylene polymerization . This paper describes Cp 2 Hf–CH 3 + sites on a weakly coordinating oxide that catalyze hydrogenolysis of iPP.…”

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confidence: 99%

A Supported Ziegler-Type Organohafnium Site Metabolizes Polypropylene

Samudrala,

Conley

2023

J. Am. Chem. Soc.

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Cp2Hf(CH3)2 reacts with silica containing strong aluminum Lewis sites to form Cp2Hf–13CH3 + paired with aluminate anions. Solid-state NMR studies show that this reaction also forms neutral organohafnium and hafnium sites lacking methyl groups. Cp2Hf–13CH3 + reacts with isotatic polypropylene (iPP, M n = 13.3 kDa; Đ = 2.4; mmmm = 94%; ∼110 C3H6/Hf) and H2 to form oils with moderate molecular weights (M n = 290–1200 Da) in good yields. The aliphatic oils show characteristic 13C{1H} NMR properties consistent with complete loss of diastereoselectivity and formation of regioirregular errors under 1 atm H2. These results show that a Ziegler–Natta-type active site is compatible in a common reaction used to digest waste plastic into smaller aliphatic fragments.

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confidence: 99%

A Supported Ziegler-Type Organohafnium Site Metabolizes Polypropylene

Samudrala,

Conley

2023

J. Am. Chem. Soc.

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“…Surface hydroxyl groups were found to serve as both Brønsted acid and base sites . However, the focus of this review is not the coordination chemistry or reaction mechanisms of supported metal complexes on metal oxide surfaces; instead, we highlight the possibilities to leverage the interaction with metal oxide surface hydroxyl groups. , …”

Section: Types Of Surfacesmentioning

confidence: 99%

“…48 However, the focus of this review is not the coordination chemistry or reaction mechanisms of supported metal complexes on metal oxide surfaces; instead, we highlight the possibilities to leverage the interaction with metal oxide surface hydroxyl groups. 48,50 Axial coordination of metal centers to the abundant hydroxyl groups on metal oxide surfaces is readily available. 15,38,40,51,52 Moreover, various types of anchoring handles were developed to create diverse and stable linkages between the surface and metal complex.…”

Section: Types Of Surfacesmentioning

confidence: 99%

“…Organometallic complexes can be introduced onto metal oxide supports either by direct bonding or via intervening ligands . Direct adsorption onto metal oxide surfaces and physical entrapment of molecules inside porous layers are common strategies to assemble such heterogenized catalysts for transformations such as water oxidation. , It is important to note that the metal/ligand can react with the oxide support in various ways. Surface hydroxyl groups were found to serve as both Brønsted acid and base sites .…”

Section: Types Of Surfacesmentioning

confidence: 99%

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Tuning Electrode Reactivity through Organometallic Complexes

Shen

Wang

et al. 2023

ACS Appl. Mater. Interfaces

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The use of molecularly modified electrodes in catalysis heralds a new paradigm in designing chemical transformations by allowing control of catalytic activity. Herein, we provide an overview of reported methods to develop electrodes functionalized with organometallic complexes and a summary of commonly used techniques for characterizing the electrode surface after immobilization. In addition, we highlight the implications of surface functionalization in catalysis to emphasize the key aspects that should be considered during the development and optimization of functionalized electrodes. Particularly, surface−molecule electronic coupling and electrostatic interactions within a hybrid system are discussed to present effective handles in tuning catalytic activity. We envision that this emerging type of hybrid catalytic system has the potential to combine the advantages of homogeneous catalysis and heterogeneous supports and could be applied to an expanded range of transformations beyond energy conversion.

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“…As pKa values are strongly dependent on solvation effects, 17 we chose first to evaluate gas phase acidity (deprotonation enthalpy, DPE) using density functional theory (DFT) (i.e. the enthalpy of the release of a proton and formation of the anion in gas phase, HAcid 18 ).…”

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109Ag NMR Chemical Shift as a Descriptor for Brønsted Acidity in Molecules and Materials

Hansen

Docherty

Cao

et al. 2023

Preprint

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A series of silver N-heterocyclic carbene (NHC) complexes of general structure [(NHC)AgX] are synthesized and characterized. Nuclear magnetic resonance (NMR) studies show that the 109Ag NMR chemical shift of the series correlates with the Brønsted acidity of the conjugate acid of X- (i.e., HX), thus establishing an acidity scale based on 109Ag NMR chemical shift. The methodology is then applied to the analysis of the Brønsted acidity of oxide materials relevant to heterogeneous catalysis using Dynamic Nuclear Polarization (DNP-)enhanced solid-state NMR spectroscopy, showcasing a novel methodology to evaluate Brønsted acidity of catalyst supports and materials.

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Effects of surface acidity on the structure of organometallics supported on oxide surfaces

Abstract: Well-defined organometallics supported on high surface area oxides are promising heterogeneous catalysts. An important design factor in these materials is how the metal interacts with the functionalities on an oxide...

Cited by 13 publications

References 176 publications

A Supported Ziegler-Type Organohafnium Site Metabolizes Polypropylene

A Supported Ziegler-Type Organohafnium Site Metabolizes Polypropylene

Tuning Electrode Reactivity through Organometallic Complexes

109Ag NMR Chemical Shift as a Descriptor for Brønsted Acidity in Molecules and Materials

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