Electrochemical Reduction of CO2 Catalyzed by Re(pyridine-oxazoline)(CO)3Cl Complexes

John K. Nganga, Christian R. Samanamu, Joseph M. Tanski, Carlos Pacheco, Cesar Saucedo, Victor S. Batista, Kyle A. Grice, Mehmed Z. Ertem, Alfredo M. Angeles-Boza

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Abstract

A series of rhenium tricarbonyl complexes coordinated by asymmetric diimine ligands containing a pyridine moiety bound to an oxazoline ring were synthesized, structurally and electrochemically characterized, and screened for CO2 reduction ability. The reported complexes are of the type Re(N-N)(CO)3Cl, with N-N = 2-(pyridin-2-yl)-4,5-dihydrooxazole (1), 5-methyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (2), and 5-phenyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (3). The electrocatalytic reduction of CO2 by these complexes was observed in a variety of solvents and proceeds more quickly in acetonitrile than in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The analysis of the catalytic cycle for electrochemical CO2 reduction by 1 in acetonitrile using density functional theory (DFT) supports the C-O bond cleavage step being the rate-determining step (RDS) (ΔG = 27.2 kcal mol-1). The dependency of the turnover frequencies (TOFs) on the donor number (DN) of the solvent also supports that C-O bond cleavage is the rate-determining step. Moreover, the calculations using explicit solvent molecules indicate that the solvent dependence likely arises from a protonation-first mechanism. Unlike other complexes derived from fac-Re(bpy)(CO)3Cl (I; bpy = 2,2′-bipyridine), in which one of the pyridyl moieties in the bpy ligand is replaced by another imine, no catalytic enhancement occurs during the first reduction potential. Remarkably, catalysts 1 and 2 display relative turnover frequencies, (icat/ip)2, up to 7 times larger than that of I.

Original languageEnglish (US)
Pages (from-to)3214-3226
Number of pages13
JournalInorganic chemistry
Volume56
Issue number6
DOIs
StatePublished - Mar 20 2017

Fingerprint

Carbon Monoxide
pyridines
acetonitrile
cleavage
Rhenium
Ligands
Dimethylformamide
ligands
Imines
Protonation
rhenium
Dimethyl Sulfoxide
imines
Density functional theory
density functional theory
catalysts
cycles
Catalysts
Molecules
pyridine

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

Cite this

Nganga, J. K., Samanamu, C. R., Tanski, J. M., Pacheco, C., Saucedo, C., Batista, V. S., ... Angeles-Boza, A. M. (2017). Electrochemical Reduction of CO2 Catalyzed by Re(pyridine-oxazoline)(CO)3Cl Complexes. Inorganic chemistry, 56(6), 3214-3226. https://doi.org/10.1021/acs.inorgchem.6b02384
Nganga, John K. ; Samanamu, Christian R. ; Tanski, Joseph M. ; Pacheco, Carlos ; Saucedo, Cesar ; Batista, Victor S. ; Grice, Kyle A. ; Ertem, Mehmed Z. ; Angeles-Boza, Alfredo M. / Electrochemical Reduction of CO2 Catalyzed by Re(pyridine-oxazoline)(CO)3Cl Complexes. In: Inorganic chemistry. 2017 ; Vol. 56, No. 6. pp. 3214-3226.
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Nganga, JK, Samanamu, CR, Tanski, JM, Pacheco, C, Saucedo, C, Batista, VS, Grice, KA, Ertem, MZ & Angeles-Boza, AM 2017, 'Electrochemical Reduction of CO2 Catalyzed by Re(pyridine-oxazoline)(CO)3Cl Complexes', Inorganic chemistry, vol. 56, no. 6, pp. 3214-3226. https://doi.org/10.1021/acs.inorgchem.6b02384

Electrochemical Reduction of CO2 Catalyzed by Re(pyridine-oxazoline)(CO)3Cl Complexes. / Nganga, John K.; Samanamu, Christian R.; Tanski, Joseph M.; Pacheco, Carlos; Saucedo, Cesar; Batista, Victor S.; Grice, Kyle A.; Ertem, Mehmed Z.; Angeles-Boza, Alfredo M.

In: Inorganic chemistry, Vol. 56, No. 6, 20.03.2017, p. 3214-3226.

Research output: Contribution to journalArticle

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T1 - Electrochemical Reduction of CO2 Catalyzed by Re(pyridine-oxazoline)(CO)3Cl Complexes

AU - Nganga, John K.

AU - Samanamu, Christian R.

AU - Tanski, Joseph M.

AU - Pacheco, Carlos

AU - Saucedo, Cesar

AU - Batista, Victor S.

AU - Grice, Kyle A.

AU - Ertem, Mehmed Z.

AU - Angeles-Boza, Alfredo M.

PY - 2017/3/20

Y1 - 2017/3/20

N2 - A series of rhenium tricarbonyl complexes coordinated by asymmetric diimine ligands containing a pyridine moiety bound to an oxazoline ring were synthesized, structurally and electrochemically characterized, and screened for CO2 reduction ability. The reported complexes are of the type Re(N-N)(CO)3Cl, with N-N = 2-(pyridin-2-yl)-4,5-dihydrooxazole (1), 5-methyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (2), and 5-phenyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (3). The electrocatalytic reduction of CO2 by these complexes was observed in a variety of solvents and proceeds more quickly in acetonitrile than in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The analysis of the catalytic cycle for electrochemical CO2 reduction by 1 in acetonitrile using density functional theory (DFT) supports the C-O bond cleavage step being the rate-determining step (RDS) (ΔG⧧ = 27.2 kcal mol-1). The dependency of the turnover frequencies (TOFs) on the donor number (DN) of the solvent also supports that C-O bond cleavage is the rate-determining step. Moreover, the calculations using explicit solvent molecules indicate that the solvent dependence likely arises from a protonation-first mechanism. Unlike other complexes derived from fac-Re(bpy)(CO)3Cl (I; bpy = 2,2′-bipyridine), in which one of the pyridyl moieties in the bpy ligand is replaced by another imine, no catalytic enhancement occurs during the first reduction potential. Remarkably, catalysts 1 and 2 display relative turnover frequencies, (icat/ip)2, up to 7 times larger than that of I.

AB - A series of rhenium tricarbonyl complexes coordinated by asymmetric diimine ligands containing a pyridine moiety bound to an oxazoline ring were synthesized, structurally and electrochemically characterized, and screened for CO2 reduction ability. The reported complexes are of the type Re(N-N)(CO)3Cl, with N-N = 2-(pyridin-2-yl)-4,5-dihydrooxazole (1), 5-methyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (2), and 5-phenyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (3). The electrocatalytic reduction of CO2 by these complexes was observed in a variety of solvents and proceeds more quickly in acetonitrile than in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). The analysis of the catalytic cycle for electrochemical CO2 reduction by 1 in acetonitrile using density functional theory (DFT) supports the C-O bond cleavage step being the rate-determining step (RDS) (ΔG⧧ = 27.2 kcal mol-1). The dependency of the turnover frequencies (TOFs) on the donor number (DN) of the solvent also supports that C-O bond cleavage is the rate-determining step. Moreover, the calculations using explicit solvent molecules indicate that the solvent dependence likely arises from a protonation-first mechanism. Unlike other complexes derived from fac-Re(bpy)(CO)3Cl (I; bpy = 2,2′-bipyridine), in which one of the pyridyl moieties in the bpy ligand is replaced by another imine, no catalytic enhancement occurs during the first reduction potential. Remarkably, catalysts 1 and 2 display relative turnover frequencies, (icat/ip)2, up to 7 times larger than that of I.

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Nganga JK, Samanamu CR, Tanski JM, Pacheco C, Saucedo C, Batista VS et al. Electrochemical Reduction of CO2 Catalyzed by Re(pyridine-oxazoline)(CO)3Cl Complexes. Inorganic chemistry. 2017 Mar 20;56(6):3214-3226. https://doi.org/10.1021/acs.inorgchem.6b02384