Three Different Fates for Phosphinidenes Generated by Photocleavage of Phospha-Wittig Reagents ArPPMe<sub>3</sub>

Shah, Shashin; Simpson, M. Cather; Smith, and Rhett C.; Protasiewicz, John D.

doi:10.1021/ja015767l

Cited by 117 publications

(67 citation statements)

References 24 publications

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“…Consider the molecules most thoroughly discussed here: Dmp-P=P-Dmp and Mes*-P=P-Mes*. Excitation of Mes*-P=P-Mes* in the ultraviolet induces irreversible CH bond-insertion into the Mes* group, most likely through a phosphinidene intermediate, to produce a phosphaindan product 62, 63. In contrast, Dmp-P=P-Dmp undergoes no irreversible photochemistry under similar conditions.…”

Section: Resultsmentioning

confidence: 99%

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Twisting the Phenyls in Aryl Diphosphenes (Ar−P═P−Ar). Significant Impact upon Lowest Energy Excited States

et al. 2009

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Aryl diphosphenes (Ar-P=P-Ar) possess features that may make them useful in photonic devices, including the possibility for photochemical E-Z isomerization. Development of good models guided by computations is hampered by poor correspondence between predicted and experimental UV/vis absorption spectra. An hypothesis that the phenyl twist angle (i.e. PPCC torsion) accounts for this discrepancy is explored, with positive findings. DFT and TDDFT (B3LYP) were applied to the phenyl-P=P-phenyl (Ph-P=P-Ph) model compound over a range of phenyl twist angles, and to the Ph-P=P-Ph cores of two crystallographically characterized diphosphenes: bis-(2,4,6-tBu 3 C 6 H 2 )-diphosphene (Mes*-P=P-Mes*) and bis-(2,6-Mes 2 C 6 H 3 )-diphosphene (Dmp-P=P-Dmp). A shallow PES is observed: the full range of phenyl twist angles is accessible for under 5 kcal/mol. The KohnSham orbitals (KS-MOs) exhibit stabilization and mixing of the two highest energy frontier orbitals -the n + and π localized primarily on the -P=P-unit. A simple, single-configuration model based upon this symmetry-breaking is shown to be consistent with the major features of the measured UV/ vis spectra of several diphosphenes. Detailed evaluation of singlet excitations, transition energies and oscillator strengths with TDDFT showed that the lowest energy transition (S 1 ← S 0 ) does not always correspond to the LUMO ← HOMO configuration. Coupling between the phenyl rings and central -P=P-destabilizes the π-π* dominated state. Hence, the S 1 is always n + -π* in nature, even with a π-type HOMO. This coupling of the ring and -P=P-π systems engenders complexity in the UV/vis absorption region, and may be the origin of the variety of photobehaviours observed in diphosphenes.

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Section: Resultsmentioning

confidence: 99%

“…In other photochemical experiments, evidence for a transient cyclotetraphosphane is sought but not found 70, 72. Photoinduced bond insertion of the phosphorus into ligand C-H or C-C bonds is also observed, perhaps through a phosphinidine intermediate 62, 63, 69, 70…”

Section: Resultsmentioning

confidence: 99%

Twisting the Phenyls in Aryl Diphosphenes (Ar−P═P−Ar). Significant Impact upon Lowest Energy Excited States

et al. 2009

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“…Frequently the free phosphinidene has been generated by reduction or photolysis [129][130][131][132][133][134][135][136][137]. However, Glueck and coworkers have reported rhodiummediated isomerization of phosphacumulenes that form 33 [138,139].…”

Section: C P-c Bond Formationmentioning

confidence: 99%

Dehydrogenative Bond-Forming Catalysis Involving Phosphines

Waterman¹

2008

COC

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This review presents developments in the young field of dehydrogenative coupling reactions of phosphines. Catalytic phosphorus-element bond formation via dehydrocoupling has rapidly expanded since the first discoveries in the mid 1990s. A survey of the available catalysts, P-P and P-E products, and mechanistic understanding is presented with emphasis on the emerging synthetic applications of this reaction.

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“…This behavior would stand in contrast to the related phosphanylidene-σ 4 -phosphoranes ArPϭ PMe 3 (Ar ϭ Dmp, Mes*, 2,6-Trip 2 C 6 H 3 ) that are thermally stable at room temperature, but extrude PMe 3 upon photolysis. [3] The presumed product of phosphinidene insertion into the carbonϪchlorine bond, chlorophosphafluorene I, has, however, proven to be much more difficult to detect than the analogous product derived from phosphinidene insertion into a carbonϪcarbon bond [Equation (1)]. It appears that the PϪCl bond in I must be more susceptible to further reduction than DcpPCl 2 .…”

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“…[24] The remarkable stability of 1 is amply demonstrated by its complete inertness to continued photolysis (by either irradiation in a 254-nm photochemical reactor or by 355-nm laser light). In this regard, 1 behaves like the terphenyl-protected diphosphenes DmpPϭPDmp [3] and ArPϭ PAr [25] (Ar ϭ 2,6-Mes 2 -4-MeC 6 H 2 ).…”

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A Robust, Reactive, and Remarkably Simple to Prepare Sterically Encumbered meta-Terphenyl Ligand

Smith

Ren

Protasiewicz

2002

Eur. J. Inorg. Chem.

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Three Different Fates for Phosphinidenes Generated by Photocleavage of Phospha-Wittig Reagents ArPPMe₃

Cited by 117 publications

References 24 publications

Twisting the Phenyls in Aryl Diphosphenes (Ar−P═P−Ar). Significant Impact upon Lowest Energy Excited States

Twisting the Phenyls in Aryl Diphosphenes (Ar−P═P−Ar). Significant Impact upon Lowest Energy Excited States

Dehydrogenative Bond-Forming Catalysis Involving Phosphines

A Robust, Reactive, and Remarkably Simple to Prepare Sterically Encumbered meta-Terphenyl Ligand

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Three Different Fates for Phosphinidenes Generated by Photocleavage of Phospha-Wittig Reagents ArPPMe3

Cited by 117 publications

References 24 publications

Twisting the Phenyls in Aryl Diphosphenes (Ar−P═P−Ar). Significant Impact upon Lowest Energy Excited States

Twisting the Phenyls in Aryl Diphosphenes (Ar−P═P−Ar). Significant Impact upon Lowest Energy Excited States

Dehydrogenative Bond-Forming Catalysis Involving Phosphines

A Robust, Reactive, and Remarkably Simple to Prepare Sterically Encumbered meta-Terphenyl Ligand

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Product

Resources

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Three Different Fates for Phosphinidenes Generated by Photocleavage of Phospha-Wittig Reagents ArPPMe₃