Two-dimensional tin-119 NMR exchange spectroscopy as a tool for the elucidation of the dynamic stereochemistry of tin compounds

Wynants, C.; Binst, G. Van; Muegge, C.; Jurkschat, Klaus; Tzschach, A.; Pepermans, Henri; Gielen, Marcel

doi:10.1021/om00129a044

Cited by 30 publications

(11 citation statements)

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“…Evaluating Rate Constants from 2D-EXSY Spectra. EXSY spectroscopy has been widely used to give reliable rate constants for chemical exchange. − Various methods for calculating rate constants from two-dimensional EXSY spectra have been discussed in detail by Perrin and Dwyer …”

Section: Resultsmentioning

confidence: 99%

“…The A-frame metathesis reactions discussed here can be easily followed by one- and two-dimensional 31 P NMR. Two-dimensional EXSY (exchange spectroscopy) NMR is a powerful technique to obtain reliable rate constants and activation parameters for systems that are in equilibrium, including isomerization − and redistribution , reactions. We report variable-temperature two-dimensional 31 P{ 1 H} EXSY NMR studies of A-frame redistribution reactions.…”

Section: Introductionmentioning

confidence: 99%

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Variable-Temperature Kinetic Analysis of a Three-Site Terminal Ligand Exchange in Nickel A-Frames by Quantitative ³¹P{¹H} EXSY NMR

et al. 1998

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Variable-temperature two-dimensional phase-sensitive 31P{1H} EXSY NMR spectroscopy was used to determine the kinetics and thermodynamics of terminal ligand redistribution in the nickel A-frames Ni2(dppm)2(CCH2)X2 (X = SCN (1), Cl (3); dppm = bis(diphenylphosphino)methane). Solutions containing 1:1 mixtures of 1 and 3 undergo terminal ligand exchange via a two-step process involving a mixed-ligand intermediate, Ni2(dppm)2(CCH2)(Cl)(SCN) (2). This type of terminal ligand exchange is characteristic of this class of compounds. One-dimensional 31P{1H} NMR spectra for the mixed-halogen or halogen/pseudo-halogen species show a strong solvent dependence. The observed NMR spectra for 2 range from a broad singlet (DMSO) to a well-resolved AA‘BB‘ multiplet (benzene) and are dependent on the rate of ligand substitution. Rate constants for the terminal ligand exchange processes in DMSO-d 6 were calculated by three methods from the 31P{1H} EXSY NMR data. From these measurements, a complete thermodynamic characterization of this exchange process was achieved. Entropies of activation calculated from Eyring plots range from −11.4 to −19.0 cal/(K mol). This implies ordering of the system during the transition state and is consistent with an associative interchange (Ia) mechanistic model. Free energy calculations show an intrinsic thermodynamic stability associated with the mixed-ligand species 2.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Variable-Temperature Kinetic Analysis of a Three-Site Terminal Ligand Exchange in Nickel A-Frames by Quantitative ³¹P{¹H} EXSY NMR

et al. 1998

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“…49 1 H-1 H EXSY is based on the exchange rate between two non-equivalent hydrogen atoms that can exchange with one another conformationally or chemically. Selective irradiation of one resonance is followed, after a mixing time t m , by detection of any perturbation, of resonances resulting from exchange processes.…”

Section: Dynamic Processesmentioning

confidence: 99%

Controlling the Pirouetting Motion in Rotaxanes by Counterion Exchange

et al. 2014

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KEYWORDS ROTAXANE • PIROUETTING • METALLACARBORANE • EXSY • MOLECULAR MACHINE 2 ABSTRACTA fine control of the pirouetting motion of rotaxanes has been achieved by using a series of metallabisdicarbollides. The latter have been used as anions in the protonated form of benzylic amide macrocycle-containing fumaramide rotaxanes. The present paper discusses the synthesis, structural and dynamic characterization of the first examples of anionic boron cluster-containing rotaxanes. In order to study the dynamic properties of such molecules, the pirouetting rate of the weakly coordinating boron cluster-containing rotaxanes with the more strongly coordinating trifluoroacetate anion (TFA -), which would form a close ion pair with the macrocycle, has been measured using the EXSY technique. Our hypothesis was that the stronger the ion pair the lower the rate of rotation due to the presence of a bigger volume of solvent to be moved. The anion would act as an anchor for the pirouetting motion. Indeed, the results show the expected trend:the rotaxane with the closely coordinating TFA -anion pirouettes most slowly and the most weakly coordinating hexabromoderivative of cobaltabisdicarbollide the fastest.

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“…The familiar NMR spectrum is the first sum, whose ;'th term represents one absorption mode peak (Figure 2b) centered at frequency w; and of width (irT2jj"1 Hz and intensity /, given by eq 6. If the phase Ij = M/ (6) factor exp(i<5;) were removed, the two terms could be distinguished as the real and imaginary parts of S(w). However, both 5; and the relationship between the oscillating Bx field and the two receiver coils are arbitrary.…”

Section: Theorymentioning

confidence: 99%

Application of two-dimensional NMR to kinetics of chemical exchange

Perrin¹,

Dwyer²

1990

Chem. Rev.

746

631

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Two-dimensional tin-119 NMR exchange spectroscopy as a tool for the elucidation of the dynamic stereochemistry of tin compounds

Cited by 30 publications

References 1 publication

Variable-Temperature Kinetic Analysis of a Three-Site Terminal Ligand Exchange in Nickel A-Frames by Quantitative ³¹P{¹H} EXSY NMR

Variable-Temperature Kinetic Analysis of a Three-Site Terminal Ligand Exchange in Nickel A-Frames by Quantitative ³¹P{¹H} EXSY NMR

Controlling the Pirouetting Motion in Rotaxanes by Counterion Exchange

Application of two-dimensional NMR to kinetics of chemical exchange

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Two-dimensional tin-119 NMR exchange spectroscopy as a tool for the elucidation of the dynamic stereochemistry of tin compounds

Cited by 30 publications

References 1 publication

Variable-Temperature Kinetic Analysis of a Three-Site Terminal Ligand Exchange in Nickel A-Frames by Quantitative 31P{1H} EXSY NMR

Variable-Temperature Kinetic Analysis of a Three-Site Terminal Ligand Exchange in Nickel A-Frames by Quantitative 31P{1H} EXSY NMR

Controlling the Pirouetting Motion in Rotaxanes by Counterion Exchange

Application of two-dimensional NMR to kinetics of chemical exchange

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Product

Resources

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Variable-Temperature Kinetic Analysis of a Three-Site Terminal Ligand Exchange in Nickel A-Frames by Quantitative ³¹P{¹H} EXSY NMR

Variable-Temperature Kinetic Analysis of a Three-Site Terminal Ligand Exchange in Nickel A-Frames by Quantitative ³¹P{¹H} EXSY NMR