Photochemistry of 9-diazo-3,6-diazafluorene: through-space or through-bond transmission of electronic effects

Li, Yu Zhuo; Schuster, Gary B.

doi:10.1021/jo00227a006

Cited by 13 publications

(5 citation statements)

References 3 publications

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“…Interestingly, these values are nearly identical to those observed for fluorenylidene (| D / hc | = 0.408 cm -1 , | E / hc | = 0.0283 cm -1 ) but are somewhat different than those reported for the positional isomers 9-diazo-1,8-diazafluorene and 9-diazo-3,6-diazafluorene (| D / hc | = 0.442 cm -1 , | E / hc | = 0.029 cm -1 and | D / hc | = 0.438 cm -1 , | E / hc | = 0.0306 cm -1 , respectively). Comparison of the ZFS parameters supports Schuster's assertion that the primary mechanism of the electronic perturbation introduced by the ring nitrogens is through bond rather than through space 6 Spectral data acquired after the photolysis of 1 (λ ≥ 455 nm) at 4 K in a 2-MeTHF glass.…”

Section: Resultssupporting

confidence: 68%

Cu(II)-Mediated Intramolecular Carbene Cation Radical Formation: Relevance to Unimolecular Metal−Ligand Radical Intermediates

et al. 2001

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We report the syntheses of the photochemically labile 9-diazo-4,5-diazafluorene (1) framework and the corresponding Cu(9-diazo-4,5-diazafluorene)(2)(NO(3))(2) compound (2). The X-ray structure of 2 reveals a 6-coordinate, tetragonal geometry with one nitrogen donor of an asymmetrically chelated diazafluorene in the equatorial position and the other defining the weak Jahn-Teller axis. The nitrate counterions bind in a monodentate fashion in the equatorial plane to complete the coordination sphere. Extended Hückel calculations reveal that the unusual solid-state structure derives from the enlarged bite angle of the fluorene skeleton and steric interactions between the adjacent hydrogen atoms in the higher energy (0.45 eV) symmetrically coordinated state. This is in contrast to Cu(py)(4)(NO(3))(2) which is 1.3 eV more stable with the nitrate counterions bound along the Jahn-Teller axis. Electron paramagnetic resonance (EPR) studies in solution reveal that the nitrates dissociate to yield 6-coordinate CuN(2)X(2)N(2)' structures with either a bound chloride ion (g(x) = 2.10, g(y) = 2.04, g(z) = 2.23, A(z) = 177 x 10(-4) cm(-1)) or a mixture of counterion and solvent (g(x)(a) = 2.05, g(y)(a) = 2.06, g(z)(a) = 2.29, A(z)(a) = 170 x 10(-4) cm(-1); g(x)(b) = 2.07, g(y)(b) = 2.08, g(z)(b) = 2.34, A(z)(b) = 155 x 10(-4) cm(-1)). Photolyses of 1 and 2 indicate loss of N(2) and formation of either carbene ([D/hc] = 0.408 cm(-1), [E/hc] = 0.0292 cm(-1)) or Cu(I)-L(*)(+) (S = (1)/(2), g = 2.0019) intermediates, which are identified by EPR, UV-vis, and time-dependent density functional theory methods. The results illustrate the important role redox active transition metals play in determining the nature of fundamental metal-ligand radical intermediates.

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Section: Resultssupporting

confidence: 68%

Cu(II)-Mediated Intramolecular Carbene Cation Radical Formation: Relevance to Unimolecular Metal−Ligand Radical Intermediates

et al. 2001

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“…The assumption was made that bulky substituents hinder the formation of diazirine cycles or cause rapid reverse reactions. This was confirmed by the fact that attempts to prepare diphenyldiazirine (108) in the same way as the spirofluorenediazirine 110a by a "dark" pathway failed, [83,84] whereas 3-alkyl-3-phenyldiazirines are known and stable. [75] Scheme 46.…”

Section: Diazoamidesmentioning

confidence: 89%

“…[108] The same reaction in benzene solution (350 nm, 10 min) also led to a low yield of the diazirine 110b (8.5 %, detected by NMR). It is interesting that reduction of the concentration of the initial diazo compound 111b resulted in reduction of the relative yield of the diazirine 110b: for a 5.5 ϫ 10 -3 m solution of 111b in MeOH the yield of 110b was 20 % whereas for a 1.2 ϫ 10 -3 m solution of 111b it was 10 % (no other characteristics of the diazirine 110b were reported).…”

Section: Diaryldiazomethanesmentioning

confidence: 93%

Valence Isomerization between Diazo Compounds and Diazirines

Korneev

2011

Eur J Org Chem

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Diazo compounds and diazirines have been separately studied in detail and are widely used in research and for applied purposes. Although the mutual isomerization of these compounds was discovered 50 years ago, it has still been only modestly investigated. Meanwhile, this type of mutual transformation has to be taken into account on every occasion when one of these compounds is used or investigated. This review discusses all main cases of mutual isomerization between diazo compounds and diazirines with the goal of providing an impulse for its rational application, as well as describing the isomerism.

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“…Although there have been no further reports of solution chemistry or spectroscopy of pyridyl or other monocyclic six-membered heteroarylcarbenes, Li and Schuster and Dürr and co-workers have described studies on various regioisomeric cyclic diaryl analogs.…”

Section: Six-membered Ring Heteroarylcarbenesmentioning

confidence: 99%

Heteroarylcarbenes

Sheridan

2013

Chem. Rev.

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Photochemistry of 9-diazo-3,6-diazafluorene: through-space or through-bond transmission of electronic effects

Cited by 13 publications

References 3 publications

Cu(II)-Mediated Intramolecular Carbene Cation Radical Formation: Relevance to Unimolecular Metal−Ligand Radical Intermediates

Cu(II)-Mediated Intramolecular Carbene Cation Radical Formation: Relevance to Unimolecular Metal−Ligand Radical Intermediates

Valence Isomerization between Diazo Compounds and Diazirines

Heteroarylcarbenes

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