A stereoselective route to medium-ring cis-1,n-dialkyl-1,n-diphosphacycloalkanes

Alder, Roger W.; Ellis, Dianne D.; Hogg, John K.; Martin, A. R.; Orpen, A. Guy; Taylor, PM

doi:10.1039/cc9960000537

Cited by 30 publications

(17 citation statements)

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“…Phosphatrane molecules are a tricyclic cage‐like heterocycles which present the possibility to have a transannular dative bond with a nitrogen or another heteroatom. The pioneer synthetic work in the groups of Alder and Verkade showed that depending of the size, substituents and environment they can adopt out:out and/or in:out conformations. In previous works, we have demonstrated that the change of the conformation can have profound implications in the nucleophilic character of the terminal phosphorous atom, and thus, the equilibrium between out:out and in:out conformation can be tuned through the interaction with Lewis acids …”

Section: Introductionmentioning

confidence: 99%

Sequestration of CO₂by Phosphatrane Molecules

et al. 2019

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The stationary points for the reaction between the CO2 and nine different phosphatranes molecules have been characterized by means of MP2 computational methods. Two minima structures have been located: a pnicogen bonded complex where one of the oxygen atoms of CO2 acts as electron donor and an adduct that presents a covalent P−C linkage. The corresponding transition state structure linking the two minima has also been characterized. In gas phase, the pnicogen bonded complex is more stable than the corresponding adduct except in one case. In contrast, the inclusion of the solvent effect (toluene and THF), reverts the stability, being in all cases the different adducts more stable than the pnicogen bonded complexes. The electronic properties of the systems have been analysed with the Quantum Theory of Atoms in Molecules (QTAIM) and Electron Density Shift (EDS) methods.

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Section: Introductionmentioning

confidence: 99%

Sequestration of CO₂by Phosphatrane Molecules

et al. 2019

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“…We have been engaged for some time in studying the chemistry of bridgehead medium-ring diphosphines and their derivatives, 3 partly for comparison with their diamine counterparts which we studied earlier. 4,5 We have reported the preparation of 1,5-diphosphabicyclo [3.3.3]undecane 1, 6 1,6diphosphabicyclo [4.3.3]dodecane 2, 7 and 1,6-diphosphabicyclo-[4.4.3]tridecane 3, 3 but found that although the protonated ion of 1,6-diphosphabicyclo [4.4.4]tetradecane 4 could be made, all attempts at deprotonation lead to deep-seated rearrangements, probably initiated by deprotonation at α-carbon (see later). 3 This suggested that these diphosphines were extremely strong bases, even though they do not possess any conventional means † Atranes are 1,5-diheteroatom derivatives of bicyclo [3.3.3]undecane with some type of bonding interaction between the two bridgehead atoms; proazaphosphatranes are derivatives of 2,5,8,9-tetraaza-1phosphabicyclo [3.3.3]undecane.…”

Section: Introductionmentioning

confidence: 99%

Superbasic bridgehead diphosphines: the effects of strain and intrabridgehead P · · · P bonding on phosphine basicity

Alder

Butts

Orpen

et al. 2001

J. Chem. Soc., Perkin Trans. 2

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The basicity order in acetonitrile for a series of phosphines is: 1,5-diphosphabicyclo [3.3.3]undecane 1 (pK a for the protonated ion ~17.9) < 1, 6-diphosphabicyclo[4.3.3]dodecane 2 (pK a ~22.5) < 1,6-diphosphabicyclo[4.4.3]tridecane 3 (pK a 27.8). The latter is therefore comparable to Schwesinger's P 1 -t-Bu base but still significantly weaker than Verkade's proazaphosphatrane bases. The pK a for the protonated ion of 1,6-diphosphabicyclo[4.4.4]tetradecane 4 could not be determined due to rearrangement probably caused by preferred deprotonation at α-carbon. However, the X-ray structure of 4HؒPF 6 ( 1 J PP 178 Hz) shows an in,out structure with a P ؒ ؒ ؒ P distance of 2.58 Å, indicative of significant bonding. Diphosphines 2 and 3 protonate to give in,out-2H ϩ ( 1 J PP 251 Hz) and in,out-3H ϩ ( 1 J PP 253 Hz), but 1H ϩ shows no P-P coupling and is believed to be out,out. Proton affinities (PA) for the bridgehead diphosphines have been calculated at the B3LYP/6-31G* level: 1, 1001, 2, 1040, 3, 1085, and 4, 1105 kJ mol Ϫ1 and are compared with PA[(t-Bu) 3 P] = 1028 kJ mol Ϫ1 . All the bridgehead diphosphines are strongly flattened and the question of how much this may contribute to their enhanced basicity, in addition to the effect of intrabridgehead bonding, is discussed.

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“…Incidentally, it is worth mentioning that a compound of type 12 with halogen atoms other than iodine was spectroscopically detected after treating 11 with halogenating reactants other than diatomics, e.g., C 2 Cl 6 18 or the Grignard species. 18,52 Due to the lack of an X-ray structure, we did not perform any computational analysis.…”

Section: Cracking In Step V Of the Open Chain 10mentioning

confidence: 99%

The atomic level mechanism of white phosphorous demolition by di-iodine

et al. 2018

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A detailed mechanism of the I 2 -induced transformation of white phosphorus into PI 3 emerges from a DFT analysis. This multi-step process implies that at any stage one P-P and two I-I bonds cleavages, associated with the formation of two P-I bonds plus an in situ generated brand new I 2 molecule.Significant electron transfer between the atoms is observed at any step, but the reactions are better defined as concerted rather than redox. Along the steepest descent to the product, no significant barrier is encountered except for the very first P 4 activation, which costs +14.6 kcal mol −1 . At the atomic level, one first I 2 molecule, a typical mild oxidant, is first involved in a linear halogen bonding interaction (XB) with one P donor, while its terminal I atom is engaged in an additional XB adduct with a second I 2 .Significant electron transfer through the combined diatomics allows the external I atom of the dangling I 3 grouping to convey electrons into the σ* level of one P-P bond with its consequent cleavage. This implies at some point the appearance of a six-membered ring, which alternatively switches its bonding and no-bonding interactions. The final transformation of the P 2 I 4 diphosphine into two PI 3 phosphines is enlightening also for the specific role of the I substituents. In fact, it is proved that an organo-diphosphine analogue hardly undergoes the separation of two phosphines, as reported in the literature. This is attributable to the particularly high donor power of the carbo-substituted P atoms, which prevents the concertedness of the reaction but favors charge separation in an unreactive ion pair.

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A stereoselective route to medium-ring cis-1,n-dialkyl-1,n-diphosphacycloalkanes

Cited by 30 publications

References 10 publications

Sequestration of CO₂by Phosphatrane Molecules

Sequestration of CO₂by Phosphatrane Molecules

Superbasic bridgehead diphosphines: the effects of strain and intrabridgehead P · · · P bonding on phosphine basicity

The atomic level mechanism of white phosphorous demolition by di-iodine

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A stereoselective route to medium-ring cis-1,n-dialkyl-1,n-diphosphacycloalkanes

Cited by 30 publications

References 10 publications

Sequestration of CO2by Phosphatrane Molecules

Sequestration of CO2by Phosphatrane Molecules

Superbasic bridgehead diphosphines: the effects of strain and intrabridgehead P · · · P bonding on phosphine basicity

The atomic level mechanism of white phosphorous demolition by di-iodine

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Sequestration of CO₂by Phosphatrane Molecules

Sequestration of CO₂by Phosphatrane Molecules