32624-91-2Relevant academic research and scientific papers
1,4-Perinaphthadiyl. Singlet- and Triplet-State Reactivity of a Conjugated Hydrocarbon Biradical
Burnett, Michael N.,Boothe, Richard,Clark, Ernest,Gisin, Markus,Hassaneen, Hamdi M.,et al.
, p. 2527 - 2538 (2007/10/02)
1,4-Perinaphthadiyl (b) was generated from the azo precursor 1 by thermal elimination of nitrogen as well as by direct and sensitized photolysis.The biradical was persistent but light sensitive at low temperature in the triplet ground state (3b) and was characterized by optical and ESR spectroscopy; kinetic and spectrographic flash photolysis was used to monitor 3b at room temperature as a transient intermediate yielding naphthocyclobutane (2), divinylnaphthalene (3), and dimers (9,10).The lifetime of 3b was reduced from τ=0.2 ms in degassed solution to 0.2 μs in air-saturated solution, and as a result, peroxides (4, 6) were formed at the expense of the hydrocarbon products.However, the dependence of the peroxide yield on oxygen pressure required that a second intermediate also interacted with oxygen.This was identified as the singlet state of b undergoing catalyzed intersystem-crossing (ISC) upon diffusional encounter with triplet oxygen; its lifetime at 300 K was estimated as 1 ns, and the energy difference between 1b and 3b as 5 kcal/mol.The efficiency of spontaneous ISC from 1b to 3b was found to increase with decreasing temperature, and the yields of the different final products (2-4, 6, 9, 10) were strongly influenced by the conditions chosen for the formation of the biradical.The chemical properties of b are strikingly different from those of the related 1,3-perinaphthadiyls c and d due to the much shorter intrinsic lifetime of 1c and 1d.
THE BEHAVIOR OF THE SINGLET AND TRIPLET SPIN STATES OF METHYLENE-BRIDGED 1,8-NAPHTHOQUINODIMETHANE WITH O2
Pagni, Richard M.,Burnett, Michael N,,Hassaneen,Hamdi M.
, p. 843 - 851 (2007/10/02)
It has been shown that thermolysis of naphthocyclopropane 8 yields the singlet 1,8-naphthoquinodimethane 7 by disrotatory ring opening.In fluid solution the singlet biradical prefers to ring close to regenerate the starting material rather than under a 1,2-hydrogen shift to yield phenalene (9).It has been demonstrated that the singlet 7 does not react with O2 or undergo intersystem crossing to ground state triplet 7.It has also been shown by an intricate set of experiments that triplet 7 is produced on photolysis of 8 and that it reacts with O2.Unfortunately, it was not possible to elucidate unequivocally the mechanism by which triplet 7 reacts with O2.
Through Bond and Through Space Interactions in the Photodimers of Acenaphthylene
Gleiter, Rolf,Gubernator, Klaus
, p. 3811 - 3817 (2007/10/02)
The He(I) photoelectron (PE) spectra of 2,3-dihydro-1,3-methano-1H-phenalene (4), tetrahydrocyclobutacenaphthylene (5) as well as α- and β-heptacyclene (6 and 7) have been recorded.The interpretation of the first bands is based on a ZDO model and semiempirical (MINDO/3) calculations.In case of the syn-dimer of acenaphthylene (7) it results a resonance integral between the two naphthalene moieties of β ca. -0.15 eV.
