Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe(IV)=O
Computational high-throughput screening is an essential tool for catalyst design, limited primarily by the efficiency with which accurate predictions can be made. In bulk heterogeneous catalysis, linear free energy relationships (LFERs) have been extensively developed to relate elementary step activ...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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American Chemical Society
2019
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| Online Access: | https://hdl.handle.net/1721.1/122918 |
| _version_ | 1826195982093647872 |
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| author | Gani, Terry Zhi Hao Kulik, Heather Janine |
| author2 | Massachusetts Institute of Technology. Department of Chemical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Chemical Engineering Gani, Terry Zhi Hao Kulik, Heather Janine |
| author_sort | Gani, Terry Zhi Hao |
| collection | MIT |
| description | Computational high-throughput screening is an essential tool for catalyst design, limited primarily by the efficiency with which accurate predictions can be made. In bulk heterogeneous catalysis, linear free energy relationships (LFERs) have been extensively developed to relate elementary step activation energies, and thus overall catalytic activity, back to the adsorption energies of key intermediates, dramatically reducing the computational cost of screening. The applicability of these LFERs to single-site catalysts remains unclear, owing to the directional, covalent metal-ligand bonds and the broader chemical space of accessible ligand scaffolds. Through a computational screen of nearly 500 model Fe(II) complexes for CH[subscript 4] hydroxylation, we observe that (1) tuning ligand field strength yields LFERs by comparably shifting energetics of the metal 3d levels that govern the stability of different intermediates and (2) distortion of the metal coordination geometry breaks these LFERs by increasing the splitting between the d[subscript xz]/d[subscript yz] and d[subscript z][superscript 2] metal states that govern reactivity. Thus, in single-site catalysts, low Brønsted-Evans-Polanyi slopes for oxo formation, which would limit peak turnover frequency achievable through ligand field tuning alone, can be overcome through structural distortions achievable in experimentally characterized compounds. Observations from this screen also motivate the placement of strong HB donors in targeted positions as a scaffold-agnostic strategy for further activity improvement. More generally, our findings motivate broader variation of coordination geometries in reactivity studies with single-site catalysts. Keywords: density functional theory; single-site catalysis; high-throughput screening; catalyst design; minimal models; linear scaling relations; methane activation; iron-oxo |
| first_indexed | 2024-09-23T10:18:58Z |
| format | Article |
| id | mit-1721.1/122918 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T10:18:58Z |
| publishDate | 2019 |
| publisher | American Chemical Society |
| record_format | dspace |
| spelling | mit-1721.1/1229182022-09-26T17:12:07Z Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe(IV)=O Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe[superscript IV]=O Gani, Terry Zhi Hao Kulik, Heather Janine Massachusetts Institute of Technology. Department of Chemical Engineering Computational high-throughput screening is an essential tool for catalyst design, limited primarily by the efficiency with which accurate predictions can be made. In bulk heterogeneous catalysis, linear free energy relationships (LFERs) have been extensively developed to relate elementary step activation energies, and thus overall catalytic activity, back to the adsorption energies of key intermediates, dramatically reducing the computational cost of screening. The applicability of these LFERs to single-site catalysts remains unclear, owing to the directional, covalent metal-ligand bonds and the broader chemical space of accessible ligand scaffolds. Through a computational screen of nearly 500 model Fe(II) complexes for CH[subscript 4] hydroxylation, we observe that (1) tuning ligand field strength yields LFERs by comparably shifting energetics of the metal 3d levels that govern the stability of different intermediates and (2) distortion of the metal coordination geometry breaks these LFERs by increasing the splitting between the d[subscript xz]/d[subscript yz] and d[subscript z][superscript 2] metal states that govern reactivity. Thus, in single-site catalysts, low Brønsted-Evans-Polanyi slopes for oxo formation, which would limit peak turnover frequency achievable through ligand field tuning alone, can be overcome through structural distortions achievable in experimentally characterized compounds. Observations from this screen also motivate the placement of strong HB donors in targeted positions as a scaffold-agnostic strategy for further activity improvement. More generally, our findings motivate broader variation of coordination geometries in reactivity studies with single-site catalysts. Keywords: density functional theory; single-site catalysis; high-throughput screening; catalyst design; minimal models; linear scaling relations; methane activation; iron-oxo United States. Office of Naval Research (Grant N0001-17-1-2956) National Science Foundation (U.S.) (Grant CBET-1704266) MIT Energy Initiative 2019-11-12T18:38:26Z 2019-11-12T18:38:26Z 2017-12-08 2017-10-22 2019-08-22T15:47:04Z Article http://purl.org/eprint/type/JournalArticle 2155-5435 https://hdl.handle.net/1721.1/122918 Gani, Terry Z. H. and Heather J. Kulik. "Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe(IV)=O.” ACS Catalysis 8, 2 (2018): 975-986 © 2017 Publisher en http://dx.doi.org/10.1021/acscatal.7b03597 ACS Catalysis Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society Other repository |
| spellingShingle | Gani, Terry Zhi Hao Kulik, Heather Janine Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe(IV)=O |
| title | Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe(IV)=O |
| title_full | Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe(IV)=O |
| title_fullStr | Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe(IV)=O |
| title_full_unstemmed | Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe(IV)=O |
| title_short | Understanding and Breaking Scaling Relations in Single-Site Catalysis: Methane to Methanol Conversion by Fe(IV)=O |
| title_sort | understanding and breaking scaling relations in single site catalysis methane to methanol conversion by fe iv o |
| url | https://hdl.handle.net/1721.1/122918 |
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