UHF CNDO/2 study of the phosphoranyl radicals and the radical anion PH3O−

Gorlov, Yu. I.; Penkovsky, Vladimir

doi:10.1016/0009-2614(75)85581-3

Cited by 11 publications

(3 citation statements)

References 20 publications

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“…Figure7. Intrinsic reaction coordinates (in mass scaled internal coordinates) (a) linking minima e-eea2 and e-aae3 via pseudoinversion transition state Vinvl, (b) linking minima e-aae3 and e-eea2 via SPa pseudorotation transition state V'roi al, (c) linking minima a-eeel and e-aae2 via SPb pseudorotation transition state 0W*4,(d) linking minima e-eea2 and e-aae3 via SPb double-pseudorotation transition state VlS'l-Energetic scaling is not uniform on the four ordinates.…”

mentioning

confidence: 99%

Ab Initio Conformational and Stereopermutational Analyses of Phosphoranyl Radicals HP(OR)3 and P(OR)4 [R = H or CH3]

Gustafson¹,

Cramer²

1995

J. Phys. Chem.

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The potential energy hypersurfaces for HnP(OH)4-, and HnP(OCH3)4-n3 n = 0 or 1, have been explored at correlated levels using polarized valence double-5 and triple-5 basis sets. Numerous local minima and several distinct types of stereopemutational transition states interconnecting them have been identified. These transition states correspond to (i) bond rotation, (ii) pseudorotation, (iii) double pseudorotation, and (iv) pseudoinversion.The stereochemical consequences of these processes are analyzed in detail as is the nature of the singly occupied molecular orbital throughout. Geometric and natural bond orbital analyses indicate the importance of stabilizing hyperconjugative interactions in these systems. The latter effect is maximized for interactions between equatorial substituents in trigonal bipyramidal (TBP) phosphoranyl structures. Unlike the TBP local minima of the mono-and dihydroxyphosphoranyls, where the unpaired electron always localizes in an equatorial site, tri-and tetrahydroxyphosphoranyl minima localize their unpaired electrons in both equatorial and apical positions.

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confidence: 99%

Ab Initio Conformational and Stereopermutational Analyses of Phosphoranyl Radicals HP(OR)3 and P(OR)4 [R = H or CH3]

Gustafson¹,

Cramer²

1995

J. Phys. Chem.

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“…1977, 99, 4383. (26) Berclaz, T.; Geoffrey, M.; Lucken, E. A. calculations also predict that (MeOPMe3) should have a * configuration only 3.4 kcal/mol above that of the TBP one. 28 When dealing with possible permutation modes, it is always necessary to remember that observed stereochemistries of reactions are being reconciled with potential overall modes. 2 equivalent to a (TR)2 process.23f) In both of these intermediates, however, the odd electron is in the apical position.…”

Section: Discussionmentioning

confidence: 99%

The reactions of ethoxy radicals with optically active tertiary phosphines. Stereochemistry of the substitution process and the question of permutation modes for the possible phosphoranyl radical intermediates

Bentrude¹,

Moriyama²,

Mueller³

et al. 1983

J. Am. Chem. Soc.

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The reactions of (-)-(S)-2, MePhPCH2Ph, and (+)-(S)-3, zi-PrMePCH2Ph, with EtO• were shown to yield substitution products MePhPOEt and n-PrMePOEt, respectively. Both reactions occur with net inversion of configuration at phosphorus. The maximum optical yields, determined at very low phosphine conversions, were 96 ± 5% for (-)-(S)-2 and 78 ± 4% for (+)-(S)-3. Optical yields are very sensitive to reaction times and conversions, because the product phosphonites are readily racemized by EtOH formed during reaction. If indeed these substitutions take place via phosphoranyl radicals, then the stereochemistry for reaction of (-)-(S)-2 is consistent with the * electronic configuration and presumed tetrahedral geometry

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“…The 19F NMR spectrum at 60 °C had a doublet at 54.1 (/psccf = 3.6 Hz). Coalescence occurred at 25 °C, and at -100 °C there was found two quartets, each line of which was split into a doublet at 52.38 and 54.15 (/fccccf =11.0…”

Section: Methodsmentioning

confidence: 98%

Some caged polycyclic phosphoranes

Campbell¹,

De'ath²,

Denney³

et al. 1976

J. Am. Chem. Soc.

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c) it must be emphasized that we have excluded from our considerations the initial generation of a phosphoranyi radical adduct with odd electron apical, a species resulting from equatorial introduction of attacking alkoxy radical (facial attack towards the electron lone pair). Such an intermediate might be expected to isomerize rapidly to the more stable odd-electron-equatorial radical with entering alkoxy group then either apical (as in 7 or 8) or equatorial (e.g., 9). Our results do not rule out such an attack but merely exclude any single or combination of attack routes (and subsequent isomerizations) which randomize the positions of R'O. and R20. in 4 (7, 8, 9). (12) T. B. Min. unpublished results from this laboratory.(13) Given the case that k~' be only greater than /q0, the conclusion re-mains the same. Under thls condition, k2(k+) would be less than 3.3 kp; but the increase in lifetimes of 8 and 9 would still result in equilibration and memory loss. (14) For experimentally and theoretically based estimates, see PAbstract: A series of caged polycyclic thiooxyphosphoranes and oxyphosphoranes has been prepared by allowing the dithietene 6, the dioxetane 14, and hexafluorobiacetyl to react with bicyclic phosphites. Those products which contain only sixmembered rings in the bicyclic moiety have NMR spectra which show that, over the temperature range investigated, there is a rapid intramolecular motion which renders the nuclei under investigation equivalent. On the other hand, introduction of one or more five-membered rings into the bicyclic moiety leads to an inhibition of this intramolecular process, and activation energies of 12-19 kcal/mol are found for these substances. The increase in activation energy is probably associated with an increase in strain in the five-membered ring(s) during the intramolecular isomerization.During the past several years Ramirez, Ugi, and their coworkers have prepared a number of caged polycyclic oxyphosphoranes by condensation of phosphites with hexafluoroacetone and hexafluorobiacetyl.2 Representative structures are 1-3. These substances' structures have been studied by cF3\r___rcF3 (CFd, 1 1 (CFA (CF3, (CF, k OLP,O O V o 1 2 3variable-temperature N M R measurements. The data show that the fluorines of the trifluoromethyl groups of 1 are equivalent over all the temperatures investigated. The same is true for compounds 2 and 3. Similarly, the hydrogens on the carbons bonded to oxygen of 1 are equivalent over the temperature range studied. Once again the same was found to be true for 2 and 3. No structure, trigonal bipyramid or square pyramid, can account for the N M R data, and it has been concluded by Ramirez and Ugi that there is a low-energy intramolecular exchange pathway for interconversion of trigonal-bipyramidal structures which renders the various nuclei equivalent. An alternative ionization-recombination mechanism has been considered and rejected on the basis of the lack of change of the 31P N M R chemical shifts with increasing polarity of solvent. It has been shown i...

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UHF CNDO/2 study of the phosphoranyl radicals and the radical anion PH3O−

Cited by 11 publications

References 20 publications

Ab Initio Conformational and Stereopermutational Analyses of Phosphoranyl Radicals HP(OR)3 and P(OR)4 [R = H or CH3]

Ab Initio Conformational and Stereopermutational Analyses of Phosphoranyl Radicals HP(OR)3 and P(OR)4 [R = H or CH3]

The reactions of ethoxy radicals with optically active tertiary phosphines. Stereochemistry of the substitution process and the question of permutation modes for the possible phosphoranyl radical intermediates

Some caged polycyclic phosphoranes

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