Theoretical DFT study of 1,3,2-dioxa-phosphoranes formation by oxidative addition of methanol on monocyclic phospholanes

Fliss, Outaf; Bessrour, Rachida; Tangour, Bahoueddine

doi:10.1016/j.theochem.2005.04.020

Cited by 10 publications

(10 citation statements)

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“…A marginal decrease in enthalpy is found by the inclusion of additional explicit methylamine molecules. The unfavorable thermodynamics of all these proton transfer events effectively rule out the nucleophilic pathway A shown in Figure …”

Section: Resultsmentioning

confidence: 98%

Intermolecular N–H Oxidative Addition of Ammonia, Alkylamines, and Arylamines to a Planar σ³-Phosphorus Compound via an Entropy-Controlled Electrophilic Mechanism

et al. 2014

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Ammonia, alkyl amines, and aryl amines are found to undergo rapid intermolecular N-H oxidative addition to a planar mononuclear σ(3)-phosphorus compound (1). The pentacoordinate phosphorane products (1·[H][NHR]) are structurally robust, permitting full characterization by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. Isothermal titration calorimetry was employed to quantify the enthalpy of the N-H oxidative addition of n-propylamine to 1 ((n)PrNH2 + 1 → 1·[H][NH(n)Pr], ΔHrxn(298) = -10.6 kcal/mol). The kinetics of n-propylamine N-H oxidative addition were monitored by in situ UV absorption spectroscopy and determination of the rate law showed an unusually large molecularity (ν = k[1][(n)PrNH2](3)). Kinetic experiments conducted over the temperature range of 10-70 °C revealed that the reaction rate decreased with increasing temperature. Activation parameters extracted from an Eyring analysis (ΔH(⧧) = -0.8 ± 0.4 kcal/mol, ΔS(⧧) = -72 ± 2 cal/(mol·K)) indicate that the cleavage of strong N-H bonds by 1 is entropy controlled due to a highly ordered, high molecularity transition state. Density functional calculations indicate that a concerted oxidative addition via a classical three-center transition structure is energetically inaccessible. Rather, a stepwise heterolytic pathway is preferred, proceeding by initial amine-assisted N-H heterolysis upon complexation to the electrophilic phosphorus center followed by rate-controlling N → P proton transfer.

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Section: Resultsmentioning

confidence: 98%

Intermolecular N–H Oxidative Addition of Ammonia, Alkylamines, and Arylamines to a Planar σ³-Phosphorus Compound via an Entropy-Controlled Electrophilic Mechanism

et al. 2014

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“…Two minima were found on both sides of the saddle point. Moreover, the electronic energy profile as a function of the intrinsic reaction coordinate (ξ) was of the same type as the universal profile for an elementary step [38]. During the transition state TSA1 illustrated in Figure 2, the dihydrogen molecule was slightly activated since the distance between the two hydrogen atoms was 0.836 Å comparing to the distance in a free H2.…”

Section: Hydrogenation Mechanism With a Phosphine Complexmentioning

confidence: 82%

“…The monitoring of the variation in the internuclear distances of the active atoms at the influence zone of the transition state is a technique that has been, increasingly, used to discuss the reaction mechanism of an elementary step [21,[38][39][40]. During this elementary step, H1 was transferred from Ru to C2 and a σ bond was created between Ru and C3.…”

Section: Hydrogenation Mechanism With a Complex With Two Phosphinesmentioning

confidence: 99%

A DFT Study of the Hexene Hydrogenation Catalysed by the Complex RuH(CO)(Cl)(PCy3): Monophosphine vs Diphosphine Paths

Hosni

Tangour²,

Achour³

2019

Preprint

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A DFT study of hexene hydrogenation catalysed by the RuH(CO)(Cl)(PCy3)2 complex is presented. The investigation explores the feasibility of two different mechanisms: the first exploits a single phosphine complex and the second uses a two phosphines complex. The energy barriers involving a hydrogen transfer have a ten kcal.mol-1 higher than the one obtained through the single-phosphine mechanism. These results confirm the experimental hypothesis claiming that the departure of a phosphine is favourable at the beginning of the reaction which is the substitution of the catalyst model RuHCl(CO)(PMe3)2 by the real catalyst RuHCl(CO)(PCy3)2 shows no significant influence on the energetic barriers of hexene hydrogenation mechanism. The most important step of the mechanism is the kinetically determining step. The heterolytic cleavage of ruthenium-complexed H2 molecule leads to the generation of two Ru-H bonds and the oxidation of the ruthenium from Ru(II) to Ru(IV). The energy profile of this step is not relative to an elementary reaction because a shouldering is observed after the transition state. This results in an unusual gradient norm profile with five extrema. This is a direct consequence of the asynchronous nature of the different processes taking place during this step. In the case of the model complex RuHCl(CO)(IMes)(PMe3) with IMes = ( N , N '-bis( mesityl)imidazol-2-ylidene), an increase of the free enthalpy of activation is observed during the kinetically determining step, which is in agreement with the experimental work.

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“…So, we plotted (figure 4) the variations of some geometrical parameters versus the reaction coordinate [40]. Figure 4 indicates that adducts reactions of formation are concerted in type.…”

Section: Page 5 Of 10mentioning

confidence: 99%

Theoretical investigation of methoxide ion reaction on the 7-methyl-4,6-dinitrobenzofuroxan

2016

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Reaction of the methoxide ion on the 7-methyl 4,6-dinitrobenzofuroxan (DNBF) 1 has been studied theoretically by means of DFT/B3LYP technique in order to interpret the kineticthermodynamic competition between the three possible compounds that are carbanion DNBF -4 and two complexed forms (2, 3) of the methoxide group in positions 5 and 7 respectively. Optimized Geometry, nbo atomic charge distribution, thermodynamic/kinetic parameters (∆ r H°T, ∆ r S°T , ∆ r G°T, ∆H*, ∆S* and ∆G*) and IRC path have been calculated for possible products and their transitional states using water as solvent. All obtained ∆ r G°T are negative, ranging from -19.16 to -42.87 kcal mol -1 , indicating the possible observation of all products but the experimenters only detected the anionic form DNBF -. Fukui indices, which were calculated by means of NBO atomic charge distribution, confirm the electrophilicity of the sites C5 and C7. Transition states barriers, ΔG* are 14.97 , 15.16 and 21.94 kcal mol -1 for the three possible products 2, 3 and 4 respectively in water. As expected, the most stable compound is the carbanion but it exhibits also the highest activation barrier. If this situation engenders formally a double kinetic-thermodynamic competition, the very weak activation energy of the two complexes in C5 and C7 makes improbable the simultaneous detection of the three expected compounds.

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Theoretical DFT study of 1,3,2-dioxa-phosphoranes formation by oxidative addition of methanol on monocyclic phospholanes

Cited by 10 publications

References 25 publications

Intermolecular N–H Oxidative Addition of Ammonia, Alkylamines, and Arylamines to a Planar σ³-Phosphorus Compound via an Entropy-Controlled Electrophilic Mechanism

Intermolecular N–H Oxidative Addition of Ammonia, Alkylamines, and Arylamines to a Planar σ³-Phosphorus Compound via an Entropy-Controlled Electrophilic Mechanism

A DFT Study of the Hexene Hydrogenation Catalysed by the Complex RuH(CO)(Cl)(PCy3): Monophosphine vs Diphosphine Paths

Theoretical investigation of methoxide ion reaction on the 7-methyl-4,6-dinitrobenzofuroxan

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Theoretical DFT study of 1,3,2-dioxa-phosphoranes formation by oxidative addition of methanol on monocyclic phospholanes

Cited by 10 publications

References 25 publications

Intermolecular N–H Oxidative Addition of Ammonia, Alkylamines, and Arylamines to a Planar σ3-Phosphorus Compound via an Entropy-Controlled Electrophilic Mechanism

Intermolecular N–H Oxidative Addition of Ammonia, Alkylamines, and Arylamines to a Planar σ3-Phosphorus Compound via an Entropy-Controlled Electrophilic Mechanism

A DFT Study of the Hexene Hydrogenation Catalysed by the Complex RuH(CO)(Cl)(PCy3): Monophosphine vs Diphosphine Paths

Theoretical investigation of methoxide ion reaction on the 7-methyl-4,6-dinitrobenzofuroxan

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Intermolecular N–H Oxidative Addition of Ammonia, Alkylamines, and Arylamines to a Planar σ³-Phosphorus Compound via an Entropy-Controlled Electrophilic Mechanism

Intermolecular N–H Oxidative Addition of Ammonia, Alkylamines, and Arylamines to a Planar σ³-Phosphorus Compound via an Entropy-Controlled Electrophilic Mechanism