A Zeolite‐Supported Molecular Ruthenium Complex with η6‐C6H6 Ligands: Chemistry Elucidated by Using Spectroscopy and Density Functional Theory

Ogino, Isao; Chen, Mingyang; Dyer, Jason; Kletnieks, Philip W.; Haw, James F.; Dixon, David A.; Gates, Bruce C.

doi:10.1002/chem.201000303

Cited by 7 publications

(6 citation statements)

References 52 publications

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“…Further evidence of the atomic dispersion of the iridium on the zeolite was the lack of detectable Ir–Ir contributions in the EXAFS spectra. Similar results have been reported for rhodium and ruthenium on this support.…”

Section: Characterization Methodssupporting

confidence: 91%

“…This evidence included the disappearance of ethylene bands, the growing-in of ethyl bands, and the observation of gas-phase ethane; intensities of metal hydride bands are often too little to allow their detection. 130,131 Comparable supported metals have been shown by IR spectroscopy to incorporate ethylene, CO, 51 benzene, 109 phenyl, 132 hydride, 108 and cyclohexene ligands. 58 In summary, IR experiments are often highly informative and should be regarded as essential for investigating reactivities of a number of supported metals and characterizing changes during catalyst treatments.…”

Section: Atomic-resolution Imagingmentioning

confidence: 99%

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Atomically Dispersed Metals on Well-Defined Supports including Zeolites and Metal–Organic Frameworks: Structure, Bonding, Reactivity, and Catalysis

2020

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When metals in supported catalysts are atomically dispersed, they are usually cationic and bonded chemically to supports. Investigations of noble metals in this class are growing rapidly, leading to discoveries of catalysts with new properties. Characterization of these materials is challenging because the metal atoms reside on surfaces that are typically nonuniform in composition and structure. We posit that understanding of structures and catalytic properties of these materials is emerging most strongly from investigations of structurally uniform catalysts (metal atoms dispersed on crystalline supports) which can be characterized incisively with atomic-resolution electron microscopy, X-ray absorption spectroscopy, and infrared spectroscopy, bolstered by density functional theory. We assess the literature of such catalysts supported on zeotype materials, metal–organic frameworks, and covalent organic frameworks. Assessing characterization, reactivity, and catalytic performance of catalysts for oxidation, hydrogenation, the water–gas shift reaction, and others, we consider metal–support interactions and ligand effects for various metal–support combinations, evaluating the degree of structural uniformity of exemplary catalysts and summarizing structure–reactivity and structure–catalytic property relationships.

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Section: Characterization Methodssupporting

confidence: 91%

Section: Atomic-resolution Imagingmentioning

confidence: 99%

Atomically Dispersed Metals on Well-Defined Supports including Zeolites and Metal–Organic Frameworks: Structure, Bonding, Reactivity, and Catalysis

2020

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“…A significant advance resulted from use of a precursor with reactive π-bonded C 2 H 4 ligands instead of the nonreactive carbonyl ligands. , They reacted Rh(C 2 H 4 ) 2 (acac) with highly dehydroxylated MgO and obtained surface-site-isolated Rh(C 2 H 4 ) 2 complexes, as evidenced by EXAFS and IR data. Because these Rh complexes already possessed reactive C 2 H 4 ligands, they provided a direct entry into a catalytic cycle for C 2 H 4 conversion and offered an opportunity for facile conversion into other organic ligands. − These studies were later extended to Ir and Ru to prepare analogous metal complexes with reactive ligands on other supports, such as MgO and zeolites. − …”

Section: Oxide-supported Atomically Dispersed Metal Complexes and Clu...mentioning

confidence: 99%

Bruce Gates: A Career in Catalysis

et al. 2020

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On the occasion of his 80th birthday, we take stock of the remarkable and ongoing career of Professor Bruce C. Gates. This Account highlights his key scientific achievements in three areas of significance: supported metal clusters and atomically dispersed metal complexes, hydroprocessing reaction networks and catalysts, and strong acid catalysis. His contributions in all three areas are noteworthy and have been sustained over 50 years. The work of his group evolved from mainly catalyst synthesis and reaction studies to also incorporate sophisticated characterization techniques based on X-ray absorption spectroscopies and improved scanning transmission electron microscopic examination of catalytic surfaces. In the course of this work, he has addressed, and contributed to the solutions of some of the most significant and challenging problems in catalysis of the last half century.

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“…5 A larger model system, Al(OR) 4 M, was used in a computational investigation of the Rh and Ru complexes on the β zeolite, where R is either H or a silanol group. 24 A third binding site could be derived from a silanol anion group in the vicinity of the Al atom and, for M II complexes, such as Ru(II) and Os(II) complexes, the anion is needed for charge balance.…”

Section: Introductionmentioning

confidence: 99%

Molecular models of site-isolated cobalt, rhodium, and iridium catalysts supported on zeolites: Ligand bond dissociation energies

Chen

Serna

et al. 2015

Computational and Theoretical Chemistry

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Synopsis Potential energy surface (PES) for the hydrogenation reaction of C 2 H 4 on a model of a single site Ir catalyst embedded in a zeolite with and without a CO ligand present in kcal/mol. The predicted results for the PES, ligand bond dissociation energies, and vibrational frequencies are in good agreement with the experimental observations. -52.1 -65.1 -48.6 *Graphical Abstract (for review) AbstractThe chemistry of zeolite-supported site-isolated cobalt, rhodium, and iridium complexes that are essentially molecular was investigated with density functional theory (DFT) and the results compared with experimentally determined spectra characterizing rhodium and iridium species formed by the reactions of Rh(C 2 H 4 ) 2 (acac) and Ir(C 2 H 4 ) 2 (acac) (acac = acetylacetonate) with acidic zeolites such as dealuminated HY zeolite. The experimental results characterize ligand exchange reactions and catalytic reactions of adsorbed ligands, including olefin hydrogenation and dimerization. Two molecular models were used to characterize various binding sites of the metal complexes in the zeolites, and the agreement between experimental and calculated infrared frequencies and metal-ligand distances determined by extended X-ray absorption fine structure spectroscopy was generally very good. The calculated structures and energies indicate a metalsupport-oxygen (M(I)-O) coordination number of two for most of the supported complexes and a value of three when the ligands include the radicals C 2 H 5 or H. The results characterizing various isomers of the supported metal complexes incorporating hydrocarbon ligands indicate that some carbene and carbyne ligands could form. Ligand bond dissociation energies (LDEs) are reported to explain the observed reactivity trends. The experimental observations of a stronger M-CO bond than M-(C 2 H 4 ) bond for both Ir and Rh match the calculated LDEs, which show that the single-ligand LDEs of the mono and dual-ligand complexes for CO are ~12 and ~15 kcal/mol higher in energy (when the metal is Rh) and ~17 and ~20 kcal/mol higher (when the metal is Ir) than the single-ligand LDEs of the mono and dual ligand complexes for C 2 H 4 , respectively. The results provide a foundation for the prediction of the catalytic properties of numerous supported metal complexes, as summarized in detail here.

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A Zeolite‐Supported Molecular Ruthenium Complex with η⁶‐C₆H₆ Ligands: Chemistry Elucidated by Using Spectroscopy and Density Functional Theory

Cited by 7 publications

References 52 publications

Atomically Dispersed Metals on Well-Defined Supports including Zeolites and Metal–Organic Frameworks: Structure, Bonding, Reactivity, and Catalysis

Atomically Dispersed Metals on Well-Defined Supports including Zeolites and Metal–Organic Frameworks: Structure, Bonding, Reactivity, and Catalysis

Bruce Gates: A Career in Catalysis

Molecular models of site-isolated cobalt, rhodium, and iridium catalysts supported on zeolites: Ligand bond dissociation energies

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