Easy access to 103Rh n.m.r. parameters of rhodium(organo) phosphine compounds via 31P detected indirect two-dimensional 31P, 103Rh{1H} n.m.r. spectroscopy

Elsevier, Cornelis J.; Ernsting, Jan Meine; Lange, Wim G. J. de

doi:10.1039/c39890000585

Cited by 15 publications

(7 citation statements)

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“…The rotational correlation time is dependent on the viscosity and temperature of the solvent according to eq 3 where η v is the bulk viscosity of the solvent, k is the Boltzmann constant, T is the temperature, and A is a constant determined by the molecular volume of the solute. Hence, the observed decrease of the line widths of Ru(Cl)(Me)(CO) 2 (i-Pr-DAB) (10) and [Ru(bpy) 3 ]Cl 2 (26) with increase of temperature is in agreement with eqs 2 and 3: the rotational correlation time decreases since T increases and the viscosity decreases.…”

Section: Discussionsupporting

confidence: 83%

“…The values found for the temperature dependence (+1.1 ppm/K for 10 ; +1.6 ppm/K for 26 ) of the chemical shift are slightly higher than those observed for e.g. δ ( 187 Os) (+0.7 ppm/K) 3e and δ ( 103 Rh) (+0.5−1 ppm/K) …”

Section: Discussioncontrasting

confidence: 58%

“…For a saturated solution of Ru(Cl)(Me)(CO) 2 (i-Pr-DAB) (10) in THF, a linear dependence of δ( 99 Ru) on the temperature between 303 and 333 K was observed (four points) which amounts to +1.1 ppm/K. A saturated solution of [Ru(bpy) 3 ]Cl 2 (26) in D 2 O exhibited a linear dependence of δ( 99 Ru) on the temperature between 293 and 353 K (four points) of +1.6 ppm/K.…”

Section: Resultsmentioning

confidence: 99%

“…δ( 187 Os) (+0.7 ppm/ K) 3e and δ( 103 Rh) (+0.5-1 ppm/K). 10 Dependence on 〈r -3 〉 d . Lower δ( 99 Ru) values are expected for larger internuclear distances Ru-X be- cause of a smaller 〈r -3 〉 d term in eq 1.…”

Section: Discussionmentioning

confidence: 99%

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⁹⁹Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

et al. 1999

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The ruthenium(II) organometallic and coordination complexes of type Ru(X)(Y)(CO) 2 -(i-Pr-DAB) (i-Pr-DAB ) 1,4-diisopropyl-1,4-diaza-1,3-butadiene; X, Y ) Cl, Br, I, Me, Et, i-Pr, neo-Pe, Ph 3 Sn, Me 3 Sn, Ph 3 Pb, Ph 3 Ge, Mn(CO) 5 , RuCp(CO) 2 ) have been analyzed by means of 99 Ru NMR spectroscopy. The 99 Ru NMR resonances for these compounds are generally sharp, allowing scalar couplings to group 14 nuclei to be observed. Correlation times τ c have been determined from NOE factors and 13 C T 1 values for selected compounds and were found to parallel the molecular weight of the compounds studied. The M-Ru-M′ and M-Ru-X complexes have 99 Ru NMR resonances in distinct chemical shift regions. In the series M-Ru-M′ a correlation between the inverse of the crystal field splitting energy ∆E and δ( 99 Ru) exists. These complexes have a HOMO which is delocalized over the M-Ru-M′ σ system and a LUMO which has predominantly π*-DAB character; therefore, (∆E) -1 is dominant in the paramagnetic shielding of the ruthenium nucleus. The difference in the observed chemical shift regions of the M-Ru-M′ and M-Ru-X compounds can be attributed to differences in d-orbital radius 〈r -3 〉 d , which is in good agreement with previously performed DFT calculations. For the Ru(I)(R)(CO) 2 (i-Pr-DAB) complexes, δ( 99 Ru) follows the same trend as for a series of iron compounds, indicating an increase of the Ru-C bond length in the series Me < Et < neo-Pe < i-Pr. This finding emphasizes the power of transition-metal NMR spectroscopy in the structural analysis of transition-metal complexes. Furthermore, 99 Ru NMR provides a tool to identify and assign isomers in mixtures of Ru-polypyridyl complexes. The 99 Ru NMR resonances of coordination isomers of various triazole-containing ruthenium complexes are found at different frequencies, which can be used to unambiguously identify coordination isomers in mixtures by means of 99 Ru NMR spectroscopy. The δ( 99 Ru) value is found to increase with increasing redox potential of the polypyridyl compounds.

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Section: Discussionsupporting

confidence: 83%

Section: Discussioncontrasting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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⁹⁹Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

et al. 1999

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“…The 103 Rh-NMR shifts were determined by 31 P, 103 Rh-HMQC measurements (with constant proton decoupling). 26,27 Every determination was carried out at least twice with different Rh-frequency offset and t1-increments to exclude folds of the signals along F1. The reference frequency were calculated with J( 103 Rh) = 3.16 MHz.…”

Section: Determination Of the Micelle Sizementioning

confidence: 99%

Rhodium catalyzed hydrogenation reactions in aqueous micellar systems as green solvents

et al. 2011

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The hydrogenation of itaconic acid and dimethyl itaconate is transferred from methanol to aqueous micellar solutions of several surfactants, e.g., SDS and Triton X-100, in order to facilitate the recovery of the catalyst. The reaction rate and selectivity strongly depends on the chosen surfactant and in some cases also on the surfactant concentration. In the best case the selectivity is the same as in methanol but the reaction rate is still lower because of a lower hydrogen solubility in water. Repetitive semi-batch experiments are chosen to demonstrate that high turn-over-numbers (.1000) can be reached in aqueous micellar solutions. No notable catalyst deactivation is observed in these experiments. The performance of micellar reaction systems is controlled by the partition coefficient of the substrates between the micelles and the continuous aqueous phase which can be predicted using the Conductor-like Screening Model for Real Solvents (COSMO-RS).

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Complexes [(P₂)Rh(hfacac)] as Model Compounds for the Fragment [(P₂)Rh] and as Highly Active Catalysts for CO₂ Hydrogenation: The Accessible Molecular Surface (AMS) Model as an Approach to Quantifying the Intrinsic Steric Properties of Chelating Ligands in Homogeneous Catalysis

Angermund

Baumann

Dinjus

et al. 1997

Chemistry A European J

143

103

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Abstract:The complexes [ (P,)Rh(hfacac)] 1 [P, = R,P-(X)-PR,] are introduced as model compounds for the investigation of the intrinsic steric properties of the [(PJRh] fragment. The ligand exchange processes that occur during the syntheses of 1 from [(cod)Rh(hfacac)] and the appropriate chelating diphosphanes 3 were studied by variable-temperature multinuclear NMR spectroscopy. The molecular structures of eight examples of 1 with systematic structural variations in 3 were determined by X-ray crystallography. The steric repulsion of the PR, groups within the chelating fragment was found to significantly influence the coordination geometry of [(P,)Rh], depending on the nature and length of the backbone (X). A linear correlation between the P-Rh-P angles in the solid state and the lo3Rh Keywords: carbon dioxide activation * homogeneous catalysis ligand effects * molecular modeling * rhodium chemical shifts reveals a similar geometric situation in solution. A unique molecular modeling approach was developed to define the accessible molecular surface (AMS) of the rhodium center within the flexible [ (PJRh] fragment. The potential of this model for application in homogeneous catalysis was exemplified by the use of 1 as catalysts in a test reaction, the hydrogenation of CO, to formic acid. Complexes 1 were found to be the most active catalyst precursors for this process in organic solvents known to date.

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Easy access to 103Rh n.m.r. parameters of rhodium(organo) phosphine compounds via 31P detected indirect two-dimensional 31P, 103Rh{1H} n.m.r. spectroscopy

Abstract: A method for the efficient detection and chemical shift determination of the insensitive 103Rh nucleus via 31P detected indirect two-dimensional 31P1103Rh{1H} n.m.r. is elaborated and its usefulness for rapid access to some new 103Rh n.m.r. data of Rhl compounds is demonstrated.

Cited by 15 publications

References 1 publication

⁹⁹Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

⁹⁹Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

Rhodium catalyzed hydrogenation reactions in aqueous micellar systems as green solvents

Complexes [(P₂)Rh(hfacac)] as Model Compounds for the Fragment [(P₂)Rh] and as Highly Active Catalysts for CO₂ Hydrogenation: The Accessible Molecular Surface (AMS) Model as an Approach to Quantifying the Intrinsic Steric Properties of Chelating Ligands in Homogeneous Catalysis

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Easy access to 103Rh n.m.r. parameters of rhodium(organo) phosphine compounds via 31P detected indirect two-dimensional 31P, 103Rh{1H} n.m.r. spectroscopy

Abstract: A method for the efficient detection and chemical shift determination of the insensitive 103Rh nucleus via 31P detected indirect two-dimensional 31P1103Rh{1H} n.m.r. is elaborated and its usefulness for rapid access to some new 103Rh n.m.r. data of Rhl compounds is demonstrated.

Cited by 15 publications

References 1 publication

99Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

99Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

Rhodium catalyzed hydrogenation reactions in aqueous micellar systems as green solvents

Complexes [(P2)Rh(hfacac)] as Model Compounds for the Fragment [(P2)Rh] and as Highly Active Catalysts for CO2 Hydrogenation: The Accessible Molecular Surface (AMS) Model as an Approach to Quantifying the Intrinsic Steric Properties of Chelating Ligands in Homogeneous Catalysis

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⁹⁹Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

⁹⁹Ru NMR Spectroscopy of Organometallic and Coordination Complexes of Ruthenium(II)

Complexes [(P₂)Rh(hfacac)] as Model Compounds for the Fragment [(P₂)Rh] and as Highly Active Catalysts for CO₂ Hydrogenation: The Accessible Molecular Surface (AMS) Model as an Approach to Quantifying the Intrinsic Steric Properties of Chelating Ligands in Homogeneous Catalysis