Study of the Bonding Properties of the New Ligands C5H3N(2-R‘)(6-CH2PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

Yang, Hong; Lugan, Noël; Mathieu, René

doi:10.1021/om960982+

Cited by 82 publications

(60 citation statements)

References 22 publications

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“…Apparently, the incorporated acetone exchanges for [D 6 ]acetone. As observed by 1 H NMR spectroscopy, dissolution of [10] in solvents other than acetone results in the decomposition to a mixture of unidentified compounds. FAB-MS spectra, obtained from an acetone/m-nitrobenzyl alcohol matrix, were inconclusive because only [(TPA)Rh] was detected as the highest mass.…”

Section: Protonation and Methylation Of The 2-rhodaoxetane Oxygenmentioning

confidence: 84%

“…This singlet disappears over a period of two days, and a signal of free Me 2 CO appears in the 1 H NMR spectrum. All other signals of [10] remain unchanged. Apparently, the incorporated acetone exchanges for [D 6 ]acetone.…”

Section: Protonation and Methylation Of The 2-rhodaoxetane Oxygenmentioning

confidence: 96%

“…The step-wise conversion of ethene complex [10] in about two weeks (Scheme 11). The low 3 J(H,H) coupling constant between the Rh-CH 2 -and -CH 2 -O fragments of [10] , similar to those for [8] 2 and [9] 2 , are in accordance with the presence of a six-membered metallacycle.…”

Section: Protonation and Methylation Of The 2-rhodaoxetane Oxygenmentioning

confidence: 99%

“…A 1 H NMR spectrum of a sample of [10]BPh 4 , isolated from non-deuterated acetone by precipitation with Et 2 O, shows a singlet (relative integral 6 H) at d 0.60 in [D 6 ]acetone. This singlet disappears over a period of two days, and a signal of free Me 2 CO appears in the 1 H NMR spectrum.…”

Section: Protonation and Methylation Of The 2-rhodaoxetane Oxygenmentioning

confidence: 99%

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2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

et al. 2000

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New cationic, pentacoordinate complexes [(TPA)Rh1(ethene)]+, [1a]+, and [(MeTPA)Rh1(ethene)]+, [1b]+, have been prepared (TPA = N,N,N-tri(2-pyridylmethyl)amine, MeTPA = N-[(6-methyl-2-pyridyl)-methyl]-N,N-di(2-pyridylmethyl)amine). Complex [1a]+ is selectively converted by aqueous HCl to [(TPA)RhIII-(ethyl)Cl]+, [2a]+. The same reaction with [1b]+ results in the [(MeTPA)RhIII-(ethyl)Cl]+ isomers [2b]+ and [2c]+. Treatment of [1a]+ and [1b]+ with aqueous H2O2 results in a selective oxygenation to the unsubstituted 2-rho-da(III)oxetanes (1-oxa-2-rhoda(III)cyclo-butanes) [(TPA)RhIII(kappa2-C,O-2-oxyethyl)]+, [3a]+, and [(MeTPA)RhIII(kappa2-C,O-2-oxyethyl)]+, [3b]+. The reactivity of 2-rhodaoxetanes [3a]+ and [3b]+ is dominated by the nucleophilic character of their 2-oxyethyl oxygen. Reaction of [3a]+ and [3b]+ with the non-coordinating acid HBAr(f)4 results in the dicationic protonated 2-rhodaoxetanes [(TPA)RhIII(kappa2-2-hydroxyethyl)]2+, [4a]2+, and [(MeTPA)RhIII(kappa2-2-hydroxyethyl)]2+, [4b]2+. These eliminate acetaldehyde at room temperature, probably via a coordinatively unsaturated kappa1-2-hydroxyethyl complex. In acetonitrile, complex [4a]2+ is stabilised as [(TPA)-RhIII(kappa1-2-hydroxyethyl)(MeCN)]2+, [5a]2+, whereas the MeTPA analogue [4b]2+ continues to eliminate acetaldehyde. Reaction of [3a]+ with NH4Cl and Mel results in the coordinatively saturated complexes [(TPA)RhIII(kappa1-2-hydroxyethyl)(Cl)]+, [6a]+, and [(TPA)-RhIII(kappa1-2-methoxyethyl)(I)+, [7a]+, respectively. Reaction of [3a]+ with NH4+ in MeCN results in formation of the dicationic metallacyclic amide [(TPA)-RhIII [kappa2-O,C-2-(acetylamino)ethyl]]2+, [9]2+, via the intermediates [4a]2+, [5a]2+ and the metallacyclic iminoester [(TPA)RhIII[kappa2-N,C-2-(acetimidoyloxy)ethyl]]2+, [8]2+. The observed overall conversion of the [Rh(I)(ethene)] complex [1a]+ to the metallacyclic amide [9]2+ via 2-rhodaoxetane [3a]+, provides a new route for the amidation of a [RhI(ethene)] fragment.

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Section: Protonation and Methylation Of The 2-rhodaoxetane Oxygenmentioning

confidence: 84%

Section: Protonation and Methylation Of The 2-rhodaoxetane Oxygenmentioning

confidence: 96%

Section: Protonation and Methylation Of The 2-rhodaoxetane Oxygenmentioning

confidence: 99%

Section: Protonation and Methylation Of The 2-rhodaoxetane Oxygenmentioning

confidence: 99%

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2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

et al. 2000

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“…[5] However, the deprotection step can be more problematic, and a number of alternative strategies to achieve this have been reported. [6][7][8][9] Nonetheless, the most commonly applied procedure is still the use of an amine, [3,[10][11][12][13][14][15] which acts as a competing Lewis base to generate the free phosphine R 3 P, and the corresponding amine-borane (R 3 N·BH 3 ) species. A large variety of amines, stoichiometry, solvent, and reaction temperatures have been reported, with some conditions taking several days to reach acceptable levels of conversion.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Phosphine Borane Deprotection with Amines: The Effects of Phosphine, Solvent and Amine on Rate and Efficiency

Lloyd‐Jones

Taylor

2015

Chemistry A European J

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The kinetics of borane transfer from simple tertiary phosphine borane adducts to a wide range of amines have been determined. All data obtained, including second-order kinetics, lack of cross-over, and negative entropies of activation for reaction of triphenylphosphine borane with quinuclidine and triethylamine, are consistent with a direct (SN 2-like) transfer process, rather than a dissociative (SN 1-like) process. The identities of the amine, phosphine, and solvent all impact substantially on the rate (k) and equilibrium (K) of the transfer, which in some cases vary by many orders of magnitude. P-to-N transfer is more efficient with cyclic amines in apolar solvents due to reduced entropic costs and ground-state destabilisation. Taken as a whole, the data allow informed optimisation of the deprotection step from the stand-point of rate, or synthetic convenience. In all cases, both reactants should be present at high initial concentration to gain kinetic benefit from the bimolecularity of the process. Ultimately, the choice of amine is dictated by the identity of the phosphine borane complex. Aryl-rich phosphine boranes are sufficiently reactive to allow use of diethylamine or pyrrolidine as a volatile low polarity solvent and reactant, whereas more alkyl-rich phosphines benefit from the use of more reactive amines, such as 1,4-diaza[2.2.2]bicyclooctane (DABCO), in apolar solvents at higher temperatures.

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Synthesis of a New Potentially Hemilabile Ligand: 1-[2-(Diphenylphosphanyl)ethyl]-3,5-dimethylpyrazole, and Comparison of Its Bonding Properties with the Related 1-[2-(Ethylamino)ethyl]-3,5-dimethylpyrazole Ligand toward RhI

Esquius

Pons

Yáñez

et al. 2002

Eur. J. Inorg. Chem.

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Study of the Bonding Properties of the New Ligands C₅H₃N(2-R‘)(6-CH₂PPhR) toward Rhodium(I). Evidence for a Dynamic Competition for Bonding between O- and N-Donor Centers When R = o-Anisyl, R‘ = Me

Cited by 82 publications

References 22 publications

2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

Mechanism of Phosphine Borane Deprotection with Amines: The Effects of Phosphine, Solvent and Amine on Rate and Efficiency

Synthesis of a New Potentially Hemilabile Ligand: 1-[2-(Diphenylphosphanyl)ethyl]-3,5-dimethylpyrazole, and Comparison of Its Bonding Properties with the Related 1-[2-(Ethylamino)ethyl]-3,5-dimethylpyrazole Ligand toward RhI

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