The infrared spectra and enthalpies of strongly bound dimers of phosphinic acids in the gas phase. (CH2Cl)2POOH and (C6H5)2POOH

Asfin, R.E.; Денисов, Г. С.; Tokhadze, K. G.

doi:10.1016/s0022-2860(01)00925-5

Cited by 40 publications

(26 citation statements)

References 18 publications

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“…An analogous equilibrium also exists for dialkyl‐ and diarylphosphinic acids and this is even more shifted towards the dimer side 72. 73 Moreover, in the presence of bases such as aniline (or toluidine) and phenanthroline, part of the acid may be present in the deprotonated form.…”

Section: Resultsmentioning

confidence: 91%

Mechanistic Study of the Palladium–Phenanthroline Catalyzed Carbonylation of Nitroarenes and Amines: Palladium–Carbonyl Intermediates and Bifunctional Effects

Ragaini

Gasperini

Cenini

et al. 2009

Chemistry A European J

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Palladium-phenanthroline complexes catalyze both the nitroarene carbonylation reaction and the amine oxidative carbonylation reaction to give, depending on the conditions, carbamates and ureas. There is evidence that the key step in both processes is the amine carbonylation. Here, we show that when the reaction is run in methanol key intermediate compounds have the general formula [Pd(RPhen)(COOMe)(2)] (1) (RPhen = 1,10-phenanthroline or one of its substituted derivatives). The kinetics of the reaction of 1 with toluidine in the presence of a carboxylic or phosphorus acid is first-order with respect to complex, acid, and toluidine. A CO atmosphere is also required for the reaction to proceed. Acid dimerization was shown not to be influential under the concentration conditions examined, but reaction between the acid and toluidine is not negligible and a correction has to be applied. Diphenylphosphinic acid is more effective than any carboxylic acid in promoting this reaction, as also observed under catalytic conditions. A series of equilibria and an irreversible acid-assisted proton transfer explain the observed data. Formation of an adduct between complexes of the kind 1 and CO was spectroscopically observed when RPhen = 2,9-Me(2)Phen. Several analogous complexes were also spectroscopically characterized and the X-ray structure of [Pd(2,9-Me(2)Phen)Cl(2)(CO)] was solved. This shows an asymmetric coordination of the nitrogen ligand. Kinetic measurements were also conducted under catalytic conditions. An Eyring plot shows that the effect of the acidic promoter is to decrease the DeltaS(double dagger) value, whereas no positive effect is observed on DeltaH(double dagger). A temperature-dependent correction for the reaction between the acid and aniline and phenanthroline present under the reaction conditions has to be applied. Comparison of the results obtained under stoichiometric and catalytic conditions strongly supports the view that 1 is involved even in the latter and that the acid is acting as a bifunctional promoter.

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Section: Resultsmentioning

confidence: 91%

Mechanistic Study of the Palladium–Phenanthroline Catalyzed Carbonylation of Nitroarenes and Amines: Palladium–Carbonyl Intermediates and Bifunctional Effects

Ragaini

Gasperini

Cenini

et al. 2009

Chemistry A European J

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“…The spectrum of the H(CH 3 OH) 3 + cation in benzene solution and in the crystal phase as the {Cl 11 } − salt is essentially the same so the structure of the cation must be very similar in both phases. Since the O⋯O distances in the H(CH 3 OH) 3 + cation are shorter than those in compounds containing isolated O−H⋯O groups (Table 2), the νOH frequency ( cba center of gravity, 1920±40 cm −1 ) is lower than, for example, in phosphinic acid dimers (2000–2070 cm −1 ) 45. Comparing the spectrum of the H(CH 3 OH) 3 + cation with the α-H 7 O 3 + cation in benzene solution (Figure 13) close similarity can be seen.…”

Section: Resultsmentioning

confidence: 94%

The Nature of the Hydrated Proton H_(aq)⁺ in Organic Solvents

et al. 2008

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“…ClO 4 -), and its negligible affinity for the free base 1-(1-naphthyl)ethylamine (NEA) prompted us to consider the possibility of dimerization of the crown ether through the POOH groups. Literature data [5][6][7][8][9][10][11][12] and theoretical calculations at the B3LYP/6-311 ? G(d,p) level of the theory also suggested the dimerization or aggregation of (R,R)-6 [4].…”

Section: Introductionmentioning

confidence: 99%

Crystal structures of crown ethers containing an alkyl diarylphosphinate or a diarylphosphinic acid unit

et al. 2010

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This paper describes the structures of pseudo-18-crown-6 compounds (2, R,R-4 and 5) in the crystals together with theoretical calculations of the electronic circular dichroism (ECD) spectra. The achiral macrocyclic phosphinic acid 5 forms hydrogen-bonded dimers in the crystal. The O1-O2 distance (2.489 Ǻ ) indicates strong H-bondings. The conformations of the macrorings of the achiral phosphinate 2 and the monomers of the achiral phosphinic acid 5 are chiral. A comparison of the torsion angles of the achiral methyl phosphinate 2 and the monomeric units of achiral 5 indicates a similar geometry. The torsion angles of the chiral methyl phosphinate (R,R)-4 differ more significantly from those in achiral methyl phosphinate 2. A negative 1 B b exciton couplet was observed in the ECD spectrum of monomeric (R,R)-6 in MeOH and H 2 O as in the spectra of (R,R)-4 in all solvents. To support the idea that (R,R)-4 has basically the same conformation in the crystal and in solution, the ECD spectrum of (R,R)-4 was calculated using the geometry of the molecule in the crystal. The calculated ECD spectrum shows a reasonable agreement with the ECD spectra obtained in solution. This shows that the steric structure observed in the crystal is predominant in solution as well.

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The infrared spectra and enthalpies of strongly bound dimers of phosphinic acids in the gas phase. (CH2Cl)2POOH and (C6H5)2POOH

Cited by 40 publications

References 18 publications

Mechanistic Study of the Palladium–Phenanthroline Catalyzed Carbonylation of Nitroarenes and Amines: Palladium–Carbonyl Intermediates and Bifunctional Effects

Mechanistic Study of the Palladium–Phenanthroline Catalyzed Carbonylation of Nitroarenes and Amines: Palladium–Carbonyl Intermediates and Bifunctional Effects

The Nature of the Hydrated Proton H_(aq)⁺ in Organic Solvents

Crystal structures of crown ethers containing an alkyl diarylphosphinate or a diarylphosphinic acid unit

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The infrared spectra and enthalpies of strongly bound dimers of phosphinic acids in the gas phase. (CH2Cl)2POOH and (C6H5)2POOH

Cited by 40 publications

References 18 publications

Mechanistic Study of the Palladium–Phenanthroline Catalyzed Carbonylation of Nitroarenes and Amines: Palladium–Carbonyl Intermediates and Bifunctional Effects

Mechanistic Study of the Palladium–Phenanthroline Catalyzed Carbonylation of Nitroarenes and Amines: Palladium–Carbonyl Intermediates and Bifunctional Effects

The Nature of the Hydrated Proton H(aq)+ in Organic Solvents

Crystal structures of crown ethers containing an alkyl diarylphosphinate or a diarylphosphinic acid unit

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The Nature of the Hydrated Proton H_(aq)⁺ in Organic Solvents