Cryptand exchange kinetics

Cox, Brian G.; Garcia-Rosas, J.; Schneider, Hermann

doi:10.1021/ja00373a017

Cited by 14 publications

(10 citation statements)

References 3 publications

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“…Stability constants of the 1 : 1 lanthanide(II1) complexes are given in Table 1 together with those of Ag+ necessary for the computation. The latter are in good agreement with those previously determined by Cox et al 19 The low stability of [AgL']' (log p < 2) precluded the determination of the stability of the L5 complexes. Values relative to L' cryptates, determined by two different competitive methods involving Ag+ and K + (in parentheses), are in good agreement.…”

Section: Stability Of Trivalent Lan Than Ide Cryp Ta Tes In Ace Ton I...supporting

confidence: 91%

Solvent effects on thermodynamic and electrochemical parameters: lanthanide cryptates in acetonitrile

Marolleau¹,

Gisselbrecht²,

Gross³

et al. 1990

J. Chem. Soc., Dalton Trans.

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Section: Stability Of Trivalent Lan Than Ide Cryp Ta Tes In Ace Ton I...supporting

confidence: 91%

Solvent effects on thermodynamic and electrochemical parameters: lanthanide cryptates in acetonitrile

Marolleau¹,

Gisselbrecht²,

Gross³

et al. 1990

J. Chem. Soc., Dalton Trans.

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“…Additional confirmation of stoichiometry was obtained by observation of the IR and NMR spectra of the organic product of MeMo(CO)3C5H5 and CO. The spectra were in agreement with literature data for MeC(0)C5H5.lla'b Analogous spectra were obtained (11) for EtC(0)C5H5 and also for MeC(0)C5Me5. b.…”

Section: Introductionsupporting

confidence: 89%

“…In bis(0-ethoxyethyl) ether at 30 °C the thermodynamic values AH = -12.6 kcal/mol and AS = -30 eu were calculated. A recent general estimate for the loss of rotational and translational entropy of CO gas in the carbonyl-insertion reaction was 36 eu.7b In the temperature range °C this corresponds to [10][11][12][13][14] kcal/mol, which must be overcome by the enthalpy term to obtain net thermodynamic stability. This illustrates the close balance of the favorable enthalpy and unfavorable entropy for reaction 1. A small change in the enthalpy of reaction could have a pronounced effect in the position of the acyl/alkyl equilibrium.…”

Section: Introductionmentioning

confidence: 99%

Heats of reaction of RMo(CO)3C5H5 (R = H, Me, Et) with phosphines and phosphites: thermodynamic study of the carbonyl-insertion reaction

et al. 1986

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The heats of reaction of HMo(CO)3C5H5 with a series of phosphines and phosphites, producing HMo(CO)2(PR3)C5H5, have been measured by solution calorimetry. The order of relative Mo-PR3 bond strengths, PMe3 = P-h-Bu3 > P(OMe)3 > PMe2Ph > PMePh2, closely resembles that determined earlier for the complexes/ac-(PR3)3Mo(CO)3. The heats of reaction of RMo(CO)3C5H5 (R = CH3, C2H5), producing the phosphine-substituted acyl complexes RC(0)Mo(CO)2(PR3)C5Hs, were also studied thermochemically. This reaction can be viewed as involving both phosphine substitution and carbonyl insertion. With use of the enthalpy of phosphine substitution of HMo(CO)3C5H5 as a model, the enthalpy of carbonyl insertion is calculated. For both R = CH3 and R = C2FI5 the carbonyl-insertion reaction is favored for more basic phosphines with a difference of about 2 kcal/mol between PMe3 (most favored) and P(OMe)3 (least favored). Carbonyl insertion into the Mo-Et bond is about 3 kcal/mol more favorable than into the Mo-CH3 bond. Attempts to prepare the unsubstituted acyls RC(0)Mo(CO)3C5H5 by carbonylation of the alkyls in THF led to facile reductive elimination of RC(0)C5H5 (35 °C, 1 atm of CO), producing Mo(CO)6. Migration of the acyl group to the coordinated cyclopentadienyl ring in the presence of CO pressure and thermodynamic instability in the absence of CO pressure explain the lack of success in preparing RC(0)Mo(CO)3C5H5 for simple alkyl groups.

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“…33,49,[51][52][53][54] However, when a solute has a more complex structure, with polar and apolar parts combined in a single molecule, different parts of the solute molecule may become preferentially solvated by either of the solvents in mixed solvents, and Á tr G becomes a more complex function of the composition. 36,42,53,[55][56][57][58][59][60][61][62][63] Indeed, Á tr G can even pass through a minimum. A good example of both types of behavior is shown by betaine-30, for which Á tr G is nearly a linear function of the volume fraction in water-ethanol mixtures, but passes through a minimum in water-acetonitrile mixtures (Fig.…”

Section: Correlations With the Composition Of The Mediummentioning

confidence: 99%

Cycloadditions in mixed aqueous solvents: the role of the water concentration

Rispens

Engberts

2005

J of Physical Organic Chem

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We examined the kinetics of a series of cycloaddition reactions in mixtures of water with methanol, acetonitrile and poly(ethylene glycol) (MW 1000). The reactions include the Diels-Alder (DA) reaction between cyclopentadiene and N-n-butylmaleimide or acridizinium bromide, the retro-Diels-Alder (RDA) reaction of 1,4,4a,9a-tetrahydro-4a-methyl-(1,4,4a,9a)-1,4-methaneanthracene-9,10-dione and the 1,3-dipolar cycloaddition of benzonitrile oxide with N-n-butylmaleimide. Plots of logk vs the molar concentration or volume fraction of water are approximately linear, but with a characteristic break around 40 M water. This break, absent for the RDA reaction, is ascribed to hydrophobic effects. Comparison with aqueous mixtures of the more hydrophobic 1-propanol shows that these mixtures induce qualitatively similar effects on the rate, but that preferential solvation effects cause the mixtures of 1-propanol to exhibit a more complex behavior of logk on composition. The results are analyzed using the Abraham-Kamlett-Taft model. The solvent effects in aqueous mixtures are not satisfactorily described by this model. For some cycloadditions, small maxima in rate are observed in highly aqueous mixtures of alcohols. The origin of these maxima and the aforementioned breaks is most likely the same.

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Cryptand exchange kinetics

Cited by 14 publications

References 3 publications

Solvent effects on thermodynamic and electrochemical parameters: lanthanide cryptates in acetonitrile

Solvent effects on thermodynamic and electrochemical parameters: lanthanide cryptates in acetonitrile

Heats of reaction of RMo(CO)3C5H5 (R = H, Me, Et) with phosphines and phosphites: thermodynamic study of the carbonyl-insertion reaction

Cycloadditions in mixed aqueous solvents: the role of the water concentration

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