Singlet−Triplet Splittings and 1,2-Hydrogen Shift Barriers for Methylphenylborenide, Methylphenylcarbene, and Methylphenylnitrenium in the Gas Phase and Solution. What a Difference a Charge Makes

Cramer, Christopher J.; Truhlar, Donald G.; Falvey, Daniel E.

doi:10.1021/ja9723390

Cited by 66 publications

(83 citation statements)

References 91 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…47 This and related DFT functionals have been shown to give quite reasonable agreement with experiment for related reactive intermediates such as carbenes and nitrenium ions. [48][49][50] ' RESULTS AND DISCUSSION Electronic State Orderings of the Phenyloxenium Ion. As shown in Table 1, the singlet-triplet gap (ΔE ST ) of the phenyloxenium ion 1 is computed to be 22.1 kcal/mol ( 1 A 1 -3 A 2 ).…”

Section: ' Computational Methodsmentioning

confidence: 99%

Phenyloxenium Ions: More Like Phenylnitrenium Ions than Isoelectronic Phenylnitrenes?

Hanway

Winter

2011

J. Am. Chem. Soc.

View full text Add to dashboard Cite

The geometries and energies of the electronic states of phenyloxenium ion 1 (Ph−O + ) were computed at the multireference CASPT2/pVTZ level of theory. Despite being isoelectronic to phenylnitrene 4, the phenyloxenium ion 1 has remarkably different energetic orderings of its electronic states. The closed-shell singlet configuration ( 1 A 1 ) is the ground state of the phenyloxenium ion 1, with a computed adiabatic energy gap of 22.1 kcal/mol to the lowest-energy triplet state ( 3 A 2 ). Open-shell singlet configurations ( 1 A 2 , 1 B 1 , 1 B 2 , 2 1 A 1 ) are significantly higher in energy (>30 kcal/mol) than the closed-shell singlet configuration. These values suggest a revision to the current assignments of the ultraviolet photoelectron spectroscopy bands for the phenoxy radical to generate the phenyloxenium ion 1. For para-substituted phenyloxenium ions, the adiabatic singlet−triplet energy gap (ΔE ST ) is found to have a positive linear free energy relationship with the Hammett-like σ + R /σ + substituent parameters; for meta substituents, the relationship is nonlinear and negatively correlated. CASPT2 analyses of the excited states of p-aminophenyloxenium ion 5 and pcyanophenyloxenium ion 10 indicate that the relative orderings of the electronic states remain largely unperturbed for these para substitutions. In contrast, meta-donor-substituted phenyloxenium ions have lowenergy open-shell states (open-shell singlet, triplet) due to stabilization of a π,π* diradical state by the donor substituent. However, all of the other phenyloxenium ions and larger aryloxenium ions (naphthyl, anthryl) included in this study have closed-shell singlet ground states. Consequently, ground-state reactions of phenyloxenium ions are anticipated to be more closely related to closed-shell singlet arylnitrenium ions (Ar−NH + ) than their isoelectronic arylnitrene (Ar−N) counterparts. Disciplines Materials Chemistry | Other Chemistry | Physical Chemistry CommentsReprinted (adapted) with permission from J. Am. Chem. Soc., 2011, 133 (13) Oxenium ions are hypovalent species of formula R-O þ . These reactive intermediates are isoelectronic with nitrenes, with a formally monovalent oxygen containing two nonbonding electron pairs. Like nitrenes, the electron-deficient nature of these intermediates makes them powerful electrophiles, further amplified by the formal positive charge on the electronegative oxygen. These species are increasingly being proposed as intermediates in useful umpolung synthetic transformations, such as the oxidative Hosomi-Sakurai reaction, 1,2 the oxidative Wagner-Meerwin transposition, 3 electrochemical oxidations of phenols and phenolates, 4,5 alkane oxidations, 6 and a wide variety of other phenolic oxidations and tautomerization reactions. 7-11 These reactions convert phenols and alkanes, many of which are derived from petrochemical feedstocks, into value-added products such as cyclohexadienones, substituted phenols, and oxidized alkanes, as well as petrochemicals like poly(1,4-phenylene ether), a high-va...

show abstract

Section: ' Computational Methodsmentioning

confidence: 99%

Phenyloxenium Ions: More Like Phenylnitrenium Ions than Isoelectronic Phenylnitrenes?

Hanway

Winter

2011

J. Am. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…The compound is 4.0 kcal mol À1 more stable than 'Möbius benzene' 5 (see Pathway I). According to previous experimental and theoretical investigations, intramolecular rearrangements in carbenes proceed via the singlest state 11,12,[37][38][39] and therefore the further mechanistic considerations are restricted to the singlest state of 8.…”

Section: Intermolecular [4 2] Cycloaddition Reaction Of Conjugated Enmentioning

confidence: 99%

Ab initio study of the mechanisms of intermolecular and intramolecular [4?+?2] cycloaddition reactions of conjugated enynes

Ananikov

2001

J. Phys. Org. Chem.

View full text Add to dashboard Cite

“…This was noted in our earlier AM1 study and is a consequence of the electronegativity difference between carbon and nitrogen. 9 In a recent DFT study, Cramer et al 35 found that markedly different chemical and electronic properties were predicted for the isoelectronic Ž y q . species, PhXMe X s B , C, N .…”

Section: Insights From Pmo Theorymentioning

confidence: 99%

Syn andanti aryl nitrenium ions

1999

View full text Add to dashboard Cite

Singlet−Triplet Splittings and 1,2-Hydrogen Shift Barriers for Methylphenylborenide, Methylphenylcarbene, and Methylphenylnitrenium in the Gas Phase and Solution. What a Difference a Charge Makes

Cited by 66 publications

References 91 publications

Phenyloxenium Ions: More Like Phenylnitrenium Ions than Isoelectronic Phenylnitrenes?

Phenyloxenium Ions: More Like Phenylnitrenium Ions than Isoelectronic Phenylnitrenes?

Ab initio study of the mechanisms of intermolecular and intramolecular [4?+?2] cycloaddition reactions of conjugated enynes

Syn andanti aryl nitrenium ions

Contact Info

Product

Resources

About