Title: Evaluating the impacts of amino acids in the second and outer coordination spheres of Rh-bis(diphosphine) complexes for CO₂ hydrogenation

Abstract

To explore the influence of a biologically inspired second and outer coordination sphere on Rh-bis(diphosphine) CO₂ hydrogenation catalysts, a series of five complexes were prepared by varying the substituents on the pendant amine in the P(Et)₂CH₂N^RCH₂P(Et)₂ ligands (P^EtN^RP^Et), where R consists of methyl ester modified amino acids, including three neutral (glycine methyl ester (GlyOMe), leucine methyl ester (LeuOMe), and phenylalanine methyl ester (PheOMe)), one acidic (aspartic acid dimethyl ester (AspOMe)) and one basic (histidine methyl ester (MeHisOMe)) amino acid esters. The turnover frequencies (TOFs) for CO₂ hydrogenation for each of these complexes were compared to those of the non-amino acid containing [Rh(depp)₂]⁺ (depp) and [Rh(P^EtN^MeP^Et)₂]⁺ (NMe) complexes. Each complex is catalytically active for CO₂ hydrogenation to formate under mild conditions in THF. Catalytic activity spanned a factor of four, with the most active species being the NMe catalyst, while the slowest were the GlyOMe and the AspOMe complexes. Finally, when compared to a similar set of catalysts with phenyl-substituted phosphorous groups, a clear contribution of the outer coordination sphere is seen for this family of CO₂ hydrogenation catalysts.

Authors:

Walsh, Aaron P.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2137-8865"

Laureanti, Joseph A. ^[1]; Katipamula, Sriram ^[2]; Chambers, Geoffrey M. ^[3]; Priyadarshani, Nilusha ^[4]; Lense, Sheri ^[5]; Bays, J. Timothy  ^[3];

• Search DOE PAGES for author "Bays, J. Timothy"
• Search DOE PAGES for ORCID "0000-0002-1784-2672"

Linehan, John C.  ^[3];

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• Search DOE PAGES for ORCID "0000-0001-8942-7163"

Shaw, Wendy J.  ^[3]

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• Search DOE PAGES for ORCID "0000-0002-4696-7415"

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1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical and Computational Sciences Directorate; Ferro Corporation, Penn Yan, NY (United States)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical and Computational Sciences Directorate; Rutgers Univ., Piscataway, NJ (United States)
3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical and Computational Sciences Directorate
4. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical and Computational Sciences Directorate; Curium, Maryland Heights, MO (United States)
5. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical and Computational Sciences Directorate; Univ. of Wisconsin-Oshkosh, Oshkosh, WI (United States)

Publication Date:

Fri Nov 30 00:00:00 EST 2018

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Molecular Electrocatalysis (CME); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1571505

Alternate Identifier(s):

OSTI ID: 1507444

Report Number(s):

PNNL-SA-139812
Journal ID: ISSN 1359-6640; FDISE6

Grant/Contract Number:  

AC05-76RL01830

Resource Type:

Accepted Manuscript

Journal Name:

Faraday Discussions

Additional Journal Information:

Journal Volume: 215; Journal ID: ISSN 1359-6640

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY