The influence of N-heterocyclic carbenes (NHC) on the reactivity of [Ru(NHC)4H]+ with H2, N2, CO and O2

Suzanne Burling, L Jonas L Haller, Elena Mas-Marza, Aitor Moreno, Stuart A Macgregor, Mary F Mahon, Paul S Pregosin, Michael K Whittlesey

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Abstract

The five-coordinate ruthenium N-heterocyclic carbene (NHC) hydrido complexes [Ru(IiPr2Me2)4H][BArF 4] (1; IiPr2Me2 = l,3-diisopropyl4,5- dimethylimidazol-2-ylidene ; ArF = 3,5-(CF3) 2C6H3), [Ru(IEt2Me2) 4H]-[BArF4] (2; IEt2Me2 = l,3-diethyl-4,5-dimethylimidazol-2-ylidene) and [Ru(IMe4) 4H][BArF4] (3; IMe4=l,3,4,5- tetramethylimidazol-2-ylidene) have been synthesised following reaction of [Ru(PPh3)3HCl] with 4-8 equivalents of the free carbenes at ambient temperature. Complexes 1-3 have been structurally characterised and show square pyramidal geometries with apical hydride ligands. In both dichloromethane or pyridine solution, 1 and 2 display very low frequency hydride signals at about (3 -41. The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct [Ru(IMe4)4(MeCN)H] [BArF4], 4. The reactivity of 1-3 towards H2 and N2 depends on the size of the N-substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts with both H2 and N2 only at low temperature and incom-pletely, while 3 affords [Ru(IMe4)4(n2H2)H] [BAr F4] (7) and [Ru(IMe4)4(N 2)H][BArF4] (8) in quantitative yield at room temperature. CO shows no selectivity, reacting with 1-3 to give [Ru(NHC) 4(CO)H][BArF4] (911). Addition of O2 to solutions of 2 and 3 leads to rapid oxidation, from which the Ru III species [Ru(NHC)4(OH)2][BAr F4] and the RuIV oxo chlorido complex [Ru(IEt2Me2)4(O)Cl][BArF 4] were isolated. DFT calculations reproduce the greater ability of 3 to bind small molecules and show relative binding strengths that follow the trend CO O2 N2 H2. 2009 Wiley-VCH Verlag GmbH Co. KGaA.
LanguageEnglish
Pages10912-10923
Number of pages12
JournalChemistry - A European Journal
Volume15
Issue number41
DOIs
StatusPublished - Oct 2009

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Carbon Monoxide
Hydrides
Ligands
Ruthenium
Methylene Chloride
Toluene
Chemical shift
Discrete Fourier transforms
Temperature
carbene
Gases
Oxidation
Molecules
Geometry

Keywords

  • Carbon monoxide
  • Dichloromethane
  • Density functional theory
  • Acetonitrile
  • Ligands

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The influence of N-heterocyclic carbenes (NHC) on the reactivity of [Ru(NHC)4H]+ with H2, N2, CO and O2. / Burling, Suzanne; Haller, L Jonas L; Mas-Marza, Elena; Moreno, Aitor; Macgregor, Stuart A; Mahon, Mary F; Pregosin, Paul S; Whittlesey, Michael K.

In: Chemistry - A European Journal, Vol. 15, No. 41, 10.2009, p. 10912-10923.

Research output: Contribution to journalArticle

Burling, S, Haller, LJL, Mas-Marza, E, Moreno, A, Macgregor, SA, Mahon, MF, Pregosin, PS & Whittlesey, MK 2009, 'The influence of N-heterocyclic carbenes (NHC) on the reactivity of [Ru(NHC)4H]+ with H2, N2, CO and O2' Chemistry - A European Journal, vol. 15, no. 41, pp. 10912-10923. DOI: 10.1002/chem.200901736
Burling S, Haller LJL, Mas-Marza E, Moreno A, Macgregor SA, Mahon MF et al. The influence of N-heterocyclic carbenes (NHC) on the reactivity of [Ru(NHC)4H]+ with H2, N2, CO and O2. Chemistry - A European Journal. 2009 Oct;15(41):10912-10923. Available from, DOI: 10.1002/chem.200901736
Burling, Suzanne ; Haller, L Jonas L ; Mas-Marza, Elena ; Moreno, Aitor ; Macgregor, Stuart A ; Mahon, Mary F ; Pregosin, Paul S ; Whittlesey, Michael K. / The influence of N-heterocyclic carbenes (NHC) on the reactivity of [Ru(NHC)4H]+ with H2, N2, CO and O2. In: Chemistry - A European Journal. 2009 ; Vol. 15, No. 41. pp. 10912-10923
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abstract = "The five-coordinate ruthenium N-heterocyclic carbene (NHC) hydrido complexes [Ru(IiPr2Me2)4H][BArF 4] (1; IiPr2Me2 = l,3-diisopropyl4,5- dimethylimidazol-2-ylidene ; ArF = 3,5-(CF3) 2C6H3), [Ru(IEt2Me2) 4H]-[BArF4] (2; IEt2Me2 = l,3-diethyl-4,5-dimethylimidazol-2-ylidene) and [Ru(IMe4) 4H][BArF4] (3; IMe4=l,3,4,5- tetramethylimidazol-2-ylidene) have been synthesised following reaction of [Ru(PPh3)3HCl] with 4-8 equivalents of the free carbenes at ambient temperature. Complexes 1-3 have been structurally characterised and show square pyramidal geometries with apical hydride ligands. In both dichloromethane or pyridine solution, 1 and 2 display very low frequency hydride signals at about (3 -41. The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct [Ru(IMe4)4(MeCN)H] [BArF4], 4. The reactivity of 1-3 towards H2 and N2 depends on the size of the N-substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts with both H2 and N2 only at low temperature and incom-pletely, while 3 affords [Ru(IMe4)4(n2H2)H] [BAr F4] (7) and [Ru(IMe4)4(N 2)H][BArF4] (8) in quantitative yield at room temperature. CO shows no selectivity, reacting with 1-3 to give [Ru(NHC) 4(CO)H][BArF4] (911). Addition of O2 to solutions of 2 and 3 leads to rapid oxidation, from which the Ru III species [Ru(NHC)4(OH)2][BAr F4] and the RuIV oxo chlorido complex [Ru(IEt2Me2)4(O)Cl][BArF 4] were isolated. DFT calculations reproduce the greater ability of 3 to bind small molecules and show relative binding strengths that follow the trend CO O2 N2 H2. 2009 Wiley-VCH Verlag GmbH Co. KGaA.",
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T1 - The influence of N-heterocyclic carbenes (NHC) on the reactivity of [Ru(NHC)4H]+ with H2, N2, CO and O2

AU - Burling,Suzanne

AU - Haller,L Jonas L

AU - Mas-Marza,Elena

AU - Moreno,Aitor

AU - Macgregor,Stuart A

AU - Mahon,Mary F

AU - Pregosin,Paul S

AU - Whittlesey,Michael K

PY - 2009/10

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N2 - The five-coordinate ruthenium N-heterocyclic carbene (NHC) hydrido complexes [Ru(IiPr2Me2)4H][BArF 4] (1; IiPr2Me2 = l,3-diisopropyl4,5- dimethylimidazol-2-ylidene ; ArF = 3,5-(CF3) 2C6H3), [Ru(IEt2Me2) 4H]-[BArF4] (2; IEt2Me2 = l,3-diethyl-4,5-dimethylimidazol-2-ylidene) and [Ru(IMe4) 4H][BArF4] (3; IMe4=l,3,4,5- tetramethylimidazol-2-ylidene) have been synthesised following reaction of [Ru(PPh3)3HCl] with 4-8 equivalents of the free carbenes at ambient temperature. Complexes 1-3 have been structurally characterised and show square pyramidal geometries with apical hydride ligands. In both dichloromethane or pyridine solution, 1 and 2 display very low frequency hydride signals at about (3 -41. The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct [Ru(IMe4)4(MeCN)H] [BArF4], 4. The reactivity of 1-3 towards H2 and N2 depends on the size of the N-substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts with both H2 and N2 only at low temperature and incom-pletely, while 3 affords [Ru(IMe4)4(n2H2)H] [BAr F4] (7) and [Ru(IMe4)4(N 2)H][BArF4] (8) in quantitative yield at room temperature. CO shows no selectivity, reacting with 1-3 to give [Ru(NHC) 4(CO)H][BArF4] (911). Addition of O2 to solutions of 2 and 3 leads to rapid oxidation, from which the Ru III species [Ru(NHC)4(OH)2][BAr F4] and the RuIV oxo chlorido complex [Ru(IEt2Me2)4(O)Cl][BArF 4] were isolated. DFT calculations reproduce the greater ability of 3 to bind small molecules and show relative binding strengths that follow the trend CO O2 N2 H2. 2009 Wiley-VCH Verlag GmbH Co. KGaA.

AB - The five-coordinate ruthenium N-heterocyclic carbene (NHC) hydrido complexes [Ru(IiPr2Me2)4H][BArF 4] (1; IiPr2Me2 = l,3-diisopropyl4,5- dimethylimidazol-2-ylidene ; ArF = 3,5-(CF3) 2C6H3), [Ru(IEt2Me2) 4H]-[BArF4] (2; IEt2Me2 = l,3-diethyl-4,5-dimethylimidazol-2-ylidene) and [Ru(IMe4) 4H][BArF4] (3; IMe4=l,3,4,5- tetramethylimidazol-2-ylidene) have been synthesised following reaction of [Ru(PPh3)3HCl] with 4-8 equivalents of the free carbenes at ambient temperature. Complexes 1-3 have been structurally characterised and show square pyramidal geometries with apical hydride ligands. In both dichloromethane or pyridine solution, 1 and 2 display very low frequency hydride signals at about (3 -41. The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct [Ru(IMe4)4(MeCN)H] [BArF4], 4. The reactivity of 1-3 towards H2 and N2 depends on the size of the N-substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts with both H2 and N2 only at low temperature and incom-pletely, while 3 affords [Ru(IMe4)4(n2H2)H] [BAr F4] (7) and [Ru(IMe4)4(N 2)H][BArF4] (8) in quantitative yield at room temperature. CO shows no selectivity, reacting with 1-3 to give [Ru(NHC) 4(CO)H][BArF4] (911). Addition of O2 to solutions of 2 and 3 leads to rapid oxidation, from which the Ru III species [Ru(NHC)4(OH)2][BAr F4] and the RuIV oxo chlorido complex [Ru(IEt2Me2)4(O)Cl][BArF 4] were isolated. DFT calculations reproduce the greater ability of 3 to bind small molecules and show relative binding strengths that follow the trend CO O2 N2 H2. 2009 Wiley-VCH Verlag GmbH Co. KGaA.

KW - Carbon monoxide

KW - Dichloromethane

KW - Density functional theory

KW - Acetonitrile

KW - Ligands

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