Tuning Zr6 Metal-Organic Framework (MOF) Nodes as Catalyst Supports: Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts

Dong Yang; Samuel O. Odoh; Joshua Borycz; Timothy C. Wang; Omar K. Farha; Joseph T. Hupp; Christopher J. Cramer; Laura Gagliardi; Bruce C. Gates

doi:10.1021/acscatal.5b02243

Tuning Zr₆ Metal-Organic Framework (MOF) Nodes as Catalyst Supports: Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts

Dong Yang, Samuel O. Odoh, Joshua Borycz, Timothy C. Wang, Omar K. Farha, Joseph T. Hupp, Christopher J. Cramer, Laura Gagliardi^*, Bruce C. Gates

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

154 Scopus citations

Abstract

The Zr₆ nodes of the metal-organic frameworks (MOFs) UiO-66 and UiO-67 are metal oxide clusters of atomic precision and can be used as catalyst supports. The bonding sites on these nodes - that is, hydrogen-bonded H₂O/OH groups on UiO-67 and non-hydrogen-bonded terminal OH groups on UiO-66 - were regulated by modulation of the MOF syntheses. Ir(C₂H₄)₂(C₅H₇O₂) complexes reacted with these sites to give site-isolated Ir(C₂H₄)₂ complexes, each anchored to the node by two Ir-O_node bonds. The supported iridium complexes on these sites have been characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and density functional theory calculations. The ethylene ligands on iridium are readily replaced by CO, and the ν_CO frequencies of the resultant complexes and those of comparable complexes reported elsewhere show that the support electron-donor tendencies increase in the order HY zeolite 蠐 UiO-66 < UiO-67 (= NU-1000) < ZrO₂ < MgO. The sharpness of the IR ν_CO bands shows that the degree of uniformity of the support bonding sites decreases in the order ZrO₂ ≈ UiO-67 ≈ NU-1000 < MgO < UiO-66 蠐 HY zeolite. The reactivity of supported Ir(CO)₂ complexes with C₂H₄ to form Ir(C₂H₄)(CO) and Ir(C₂H₄)₂(CO) is influenced by the support electron-donor properties, with the reactivity increasing in the order MgO = ZrO₂ = NU-1000 (not reactive) < UiO-66 < UiO-67 蠐 HY zeolite. Density functional theory calculations characterizing the complexes supported on NU-1000, UiO-66/67, and HY zeolite concur with the use of the calculated ν_CO bands as indicators of electron-donor properties of the supported metal catalysts. Our calculations also show that the reactivity of the supported Ir(CO)₂ complexes with C₂H₄ is correlated with the electron-donor properties of the iridium center. The supported Ir(C₂H₄)₂ samples are precatalysts for ethylene hydrogenation and ethylene dimerization, with the activity for each reaction increasing with increasing electron-withdrawing strength of the support.

Original language	English (US)
Pages (from-to)	235-247
Number of pages	13
Journal	ACS Catalysis
Volume	6
Issue number	1
DOIs	https://doi.org/10.1021/acscatal.5b02243
State	Published - Jan 4 2016

Funding

This work was supported as part of the Inorganometallic Catalyst Design Center, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Award No. DESC0012702. The authors acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota for providing the computational resources.

Keywords

catalyst supports
ethylene dimerization
ethylene hydrogenation
iridium carbonyl complexes
iridium ethylene complexes
metal-organic framework nodes

ASJC Scopus subject areas

Catalysis
General Chemistry

Access to Document

10.1021/acscatal.5b02243

Cite this

Yang, D., Odoh, S. O., Borycz, J., Wang, T. C., Farha, O. K., Hupp, J. T., Cramer, C. J., Gagliardi, L., & Gates, B. C. (2016). Tuning Zr₆ Metal-Organic Framework (MOF) Nodes as Catalyst Supports: Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts. ACS Catalysis, 6(1), 235-247. https://doi.org/10.1021/acscatal.5b02243

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title = "Tuning Zr6 Metal-Organic Framework (MOF) Nodes as Catalyst Supports: Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts",

abstract = "The Zr6 nodes of the metal-organic frameworks (MOFs) UiO-66 and UiO-67 are metal oxide clusters of atomic precision and can be used as catalyst supports. The bonding sites on these nodes - that is, hydrogen-bonded H2O/OH groups on UiO-67 and non-hydrogen-bonded terminal OH groups on UiO-66 - were regulated by modulation of the MOF syntheses. Ir(C2H4)2(C5H7O2) complexes reacted with these sites to give site-isolated Ir(C2H4)2 complexes, each anchored to the node by two Ir-Onode bonds. The supported iridium complexes on these sites have been characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and density functional theory calculations. The ethylene ligands on iridium are readily replaced by CO, and the νCO frequencies of the resultant complexes and those of comparable complexes reported elsewhere show that the support electron-donor tendencies increase in the order HY zeolite 蠐 UiO-66 < UiO-67 (= NU-1000) < ZrO2 < MgO. The sharpness of the IR νCO bands shows that the degree of uniformity of the support bonding sites decreases in the order ZrO2 ≈ UiO-67 ≈ NU-1000 < MgO < UiO-66 蠐 HY zeolite. The reactivity of supported Ir(CO)2 complexes with C2H4 to form Ir(C2H4)(CO) and Ir(C2H4)2(CO) is influenced by the support electron-donor properties, with the reactivity increasing in the order MgO = ZrO2 = NU-1000 (not reactive) < UiO-66 < UiO-67 蠐 HY zeolite. Density functional theory calculations characterizing the complexes supported on NU-1000, UiO-66/67, and HY zeolite concur with the use of the calculated νCO bands as indicators of electron-donor properties of the supported metal catalysts. Our calculations also show that the reactivity of the supported Ir(CO)2 complexes with C2H4 is correlated with the electron-donor properties of the iridium center. The supported Ir(C2H4)2 samples are precatalysts for ethylene hydrogenation and ethylene dimerization, with the activity for each reaction increasing with increasing electron-withdrawing strength of the support.",

keywords = "catalyst supports, ethylene dimerization, ethylene hydrogenation, iridium carbonyl complexes, iridium ethylene complexes, metal-organic framework nodes",

author = "Dong Yang and Odoh, {Samuel O.} and Joshua Borycz and Wang, {Timothy C.} and Farha, {Omar K.} and Hupp, {Joseph T.} and Cramer, {Christopher J.} and Laura Gagliardi and Gates, {Bruce C.}",

note = "Publisher Copyright: {\textcopyright} 2015 American Chemical Society.",

year = "2016",

month = jan,

day = "4",

doi = "10.1021/acscatal.5b02243",

language = "English (US)",

volume = "6",

pages = "235--247",

journal = "ACS Catalysis",

issn = "2155-5435",

publisher = "American Chemical Society",

number = "1",

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Yang, D, Odoh, SO, Borycz, J, Wang, TC, Farha, OK , Hupp, JT, Cramer, CJ, Gagliardi, L & Gates, BC 2016, 'Tuning Zr₆ Metal-Organic Framework (MOF) Nodes as Catalyst Supports: Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts', ACS Catalysis, vol. 6, no. 1, pp. 235-247. https://doi.org/10.1021/acscatal.5b02243

TY - JOUR

T1 - Tuning Zr6 Metal-Organic Framework (MOF) Nodes as Catalyst Supports

T2 - Site Densities and Electron-Donor Properties Influence Molecular Iridium Complexes as Ethylene Conversion Catalysts

AU - Yang, Dong

AU - Odoh, Samuel O.

AU - Borycz, Joshua

AU - Wang, Timothy C.

AU - Farha, Omar K.

AU - Hupp, Joseph T.

AU - Cramer, Christopher J.

AU - Gagliardi, Laura

AU - Gates, Bruce C.

PY - 2016/1/4

Y1 - 2016/1/4

N2 - The Zr6 nodes of the metal-organic frameworks (MOFs) UiO-66 and UiO-67 are metal oxide clusters of atomic precision and can be used as catalyst supports. The bonding sites on these nodes - that is, hydrogen-bonded H2O/OH groups on UiO-67 and non-hydrogen-bonded terminal OH groups on UiO-66 - were regulated by modulation of the MOF syntheses. Ir(C2H4)2(C5H7O2) complexes reacted with these sites to give site-isolated Ir(C2H4)2 complexes, each anchored to the node by two Ir-Onode bonds. The supported iridium complexes on these sites have been characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and density functional theory calculations. The ethylene ligands on iridium are readily replaced by CO, and the νCO frequencies of the resultant complexes and those of comparable complexes reported elsewhere show that the support electron-donor tendencies increase in the order HY zeolite 蠐 UiO-66 < UiO-67 (= NU-1000) < ZrO2 < MgO. The sharpness of the IR νCO bands shows that the degree of uniformity of the support bonding sites decreases in the order ZrO2 ≈ UiO-67 ≈ NU-1000 < MgO < UiO-66 蠐 HY zeolite. The reactivity of supported Ir(CO)2 complexes with C2H4 to form Ir(C2H4)(CO) and Ir(C2H4)2(CO) is influenced by the support electron-donor properties, with the reactivity increasing in the order MgO = ZrO2 = NU-1000 (not reactive) < UiO-66 < UiO-67 蠐 HY zeolite. Density functional theory calculations characterizing the complexes supported on NU-1000, UiO-66/67, and HY zeolite concur with the use of the calculated νCO bands as indicators of electron-donor properties of the supported metal catalysts. Our calculations also show that the reactivity of the supported Ir(CO)2 complexes with C2H4 is correlated with the electron-donor properties of the iridium center. The supported Ir(C2H4)2 samples are precatalysts for ethylene hydrogenation and ethylene dimerization, with the activity for each reaction increasing with increasing electron-withdrawing strength of the support.

AB - The Zr6 nodes of the metal-organic frameworks (MOFs) UiO-66 and UiO-67 are metal oxide clusters of atomic precision and can be used as catalyst supports. The bonding sites on these nodes - that is, hydrogen-bonded H2O/OH groups on UiO-67 and non-hydrogen-bonded terminal OH groups on UiO-66 - were regulated by modulation of the MOF syntheses. Ir(C2H4)2(C5H7O2) complexes reacted with these sites to give site-isolated Ir(C2H4)2 complexes, each anchored to the node by two Ir-Onode bonds. The supported iridium complexes on these sites have been characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and density functional theory calculations. The ethylene ligands on iridium are readily replaced by CO, and the νCO frequencies of the resultant complexes and those of comparable complexes reported elsewhere show that the support electron-donor tendencies increase in the order HY zeolite 蠐 UiO-66 < UiO-67 (= NU-1000) < ZrO2 < MgO. The sharpness of the IR νCO bands shows that the degree of uniformity of the support bonding sites decreases in the order ZrO2 ≈ UiO-67 ≈ NU-1000 < MgO < UiO-66 蠐 HY zeolite. The reactivity of supported Ir(CO)2 complexes with C2H4 to form Ir(C2H4)(CO) and Ir(C2H4)2(CO) is influenced by the support electron-donor properties, with the reactivity increasing in the order MgO = ZrO2 = NU-1000 (not reactive) < UiO-66 < UiO-67 蠐 HY zeolite. Density functional theory calculations characterizing the complexes supported on NU-1000, UiO-66/67, and HY zeolite concur with the use of the calculated νCO bands as indicators of electron-donor properties of the supported metal catalysts. Our calculations also show that the reactivity of the supported Ir(CO)2 complexes with C2H4 is correlated with the electron-donor properties of the iridium center. The supported Ir(C2H4)2 samples are precatalysts for ethylene hydrogenation and ethylene dimerization, with the activity for each reaction increasing with increasing electron-withdrawing strength of the support.

KW - catalyst supports

KW - ethylene dimerization

KW - ethylene hydrogenation

KW - iridium carbonyl complexes

KW - iridium ethylene complexes

KW - metal-organic framework nodes

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