Dehydrogenation of formic acid by Ir-bisMETAMORPhos complexes: Experimental and computational insight into the role of a cooperative ligand

Sander Oldenhof; Martin Lutz; Bas De Bruin; Jarl Ivar Van Der Vlugt; Joost N H Reek

doi:10.1039/c4sc02555e

Dehydrogenation of formic acid by Ir-bisMETAMORPhos complexes: Experimental and computational insight into the role of a cooperative ligand

Sander Oldenhof, Martin Lutz, Bas De Bruin, Jarl Ivar Van Der Vlugt, Joost N H Reek^*

^*Corresponding author for this work

Academic Medical Center

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

Abstract

The synthesis and tautomeric nature of three xanthene-based bisMETAMORPhos ligands (La-Lc) is reported. Coordination of these bis(sulfonamidophosphines) to Ir(acac)(cod) initially leads to the formation of Ir^I(L^H) species (1a), which convert via formal oxidative addition of the ligand to Ir^III(L) monohydride complexes 2a-c. The rate for this step strongly depends on the ligand employed. Ir^III complexes 2a-c were applied in the base-free dehydrogenation of formic acid, reaching turnover frequencies of 3090, 877 and 1791 h^-1, respectively. The dual role of the ligand in the mechanism of the dehydrogenation reaction was studied by ¹H and ³¹P NMR spectroscopy and DFT calculations. Besides functioning as an internal base, bisMETAMORPhos also assists in the pre-assembly of formic acid within the Ir-coordination sphere and aids in stabilizing the rate-determining transition state through hydrogen-bonding.

Original language	English
Pages (from-to)	1027-1034
Number of pages	8
Journal	Chemical Science
Volume	6
Issue number	2
DOIs	https://doi.org/10.1039/c4sc02555e
Publication status	Published - 1 Feb 2015

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title = "Dehydrogenation of formic acid by Ir-bisMETAMORPhos complexes: Experimental and computational insight into the role of a cooperative ligand",

abstract = "The synthesis and tautomeric nature of three xanthene-based bisMETAMORPhos ligands (La-Lc) is reported. Coordination of these bis(sulfonamidophosphines) to Ir(acac)(cod) initially leads to the formation of IrI(LH) species (1a), which convert via formal oxidative addition of the ligand to IrIII(L) monohydride complexes 2a-c. The rate for this step strongly depends on the ligand employed. IrIII complexes 2a-c were applied in the base-free dehydrogenation of formic acid, reaching turnover frequencies of 3090, 877 and 1791 h-1, respectively. The dual role of the ligand in the mechanism of the dehydrogenation reaction was studied by 1H and 31P NMR spectroscopy and DFT calculations. Besides functioning as an internal base, bisMETAMORPhos also assists in the pre-assembly of formic acid within the Ir-coordination sphere and aids in stabilizing the rate-determining transition state through hydrogen-bonding.",

author = "Sander Oldenhof and Martin Lutz and {De Bruin}, Bas and {Van Der Vlugt}, {Jarl Ivar} and Reek, {Joost N H}",

year = "2015",

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doi = "10.1039/c4sc02555e",

language = "English",

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TY - JOUR

T1 - Dehydrogenation of formic acid by Ir-bisMETAMORPhos complexes

T2 - Experimental and computational insight into the role of a cooperative ligand

AU - Oldenhof, Sander

AU - Lutz, Martin

AU - De Bruin, Bas

AU - Van Der Vlugt, Jarl Ivar

AU - Reek, Joost N H

PY - 2015/2/1

Y1 - 2015/2/1

N2 - The synthesis and tautomeric nature of three xanthene-based bisMETAMORPhos ligands (La-Lc) is reported. Coordination of these bis(sulfonamidophosphines) to Ir(acac)(cod) initially leads to the formation of IrI(LH) species (1a), which convert via formal oxidative addition of the ligand to IrIII(L) monohydride complexes 2a-c. The rate for this step strongly depends on the ligand employed. IrIII complexes 2a-c were applied in the base-free dehydrogenation of formic acid, reaching turnover frequencies of 3090, 877 and 1791 h-1, respectively. The dual role of the ligand in the mechanism of the dehydrogenation reaction was studied by 1H and 31P NMR spectroscopy and DFT calculations. Besides functioning as an internal base, bisMETAMORPhos also assists in the pre-assembly of formic acid within the Ir-coordination sphere and aids in stabilizing the rate-determining transition state through hydrogen-bonding.

AB - The synthesis and tautomeric nature of three xanthene-based bisMETAMORPhos ligands (La-Lc) is reported. Coordination of these bis(sulfonamidophosphines) to Ir(acac)(cod) initially leads to the formation of IrI(LH) species (1a), which convert via formal oxidative addition of the ligand to IrIII(L) monohydride complexes 2a-c. The rate for this step strongly depends on the ligand employed. IrIII complexes 2a-c were applied in the base-free dehydrogenation of formic acid, reaching turnover frequencies of 3090, 877 and 1791 h-1, respectively. The dual role of the ligand in the mechanism of the dehydrogenation reaction was studied by 1H and 31P NMR spectroscopy and DFT calculations. Besides functioning as an internal base, bisMETAMORPhos also assists in the pre-assembly of formic acid within the Ir-coordination sphere and aids in stabilizing the rate-determining transition state through hydrogen-bonding.

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DO - 10.1039/c4sc02555e

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SN - 2041-6520

VL - 6

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EP - 1034

JO - Chemical Science

JF - Chemical Science

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ER -

Dehydrogenation of formic acid by Ir-bisMETAMORPhos complexes: Experimental and computational insight into the role of a cooperative ligand

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