102725-10-0Relevant academic research and scientific papers
Di(9-anthryl)carbene revisited. Product analysis and spectroscopic studies
Yoshida, Ken-Ichi,Iiba, Eiji,Nozaki, Yoshinori,Hirai, Katsuyuki,Takahashi, Yasutake,Tomioka, Hideo,Lin, Cheng-Tung,Gaspar, Peter P.
, p. 1509 - 1522 (2004)
Irradiation (λ > 300 nm) of di(9-anthryl)diazomethane (1) in degassed benzene gave the trimer (3) of dianthrylcarbene (2) as the main product along with a small amount of a tetramer (4). The structures of those oligomers were characterized as caged compounds produced as a result of three- and four-fold coupling at the 10 and 10′ positions of 2. Photolysis of 1 in the presence of oxygen with short wavelength UV light resulted in the formation of di(9-anthryl) ketone (5) and anthraquinone (6), while similar irradiation with a longer wavelength light gave 5 and 9-anthryl 9-anthracenecarboxylate (9), which was found to give 6 upon irradiation with a short wavelength light in the presence of oxygen. On the other hand, the photolysis of 4 gave 3 as the main product, while 3 was almost completely photostable under similar conditions. However, irradiation of both 3 and 4 in the presence of oxygen gave 6. In order to elucidate the reactions observed, we carried out spectroscopic studies (matrix EPR and UV/vis spectroscopies as well as laser flash photolysis) with 1, 3, and 4. These studies revealed that 3 generated a trimer diradical (10) formed as a result of C-C bond cleavage upon irradiation and that 10 reformed 3 almost exclusively, while similar photolysis of 1 and 4 generated the same two transient species, 10 and a dimer diradical. It is proposed that triplet carbene 2 equilibrates with the dimer diradical 2-2 and that the main decay pathway of this mixture is to generate the trimer diradical 10 while dimer diradical 2-2 undergoes coupling to produce the tetramer 4. The structure of the triplet carbene in equilibrium with diradicals is also discussed.
The Unusual Reactivity of 9,9'-Dianthrylcarbene
Astles, D. J.,Girard, M.,Griller, D.,Kolt, R. J.,Wayner, D. D. M.
, p. 6053 - 6057 (1988)
9,9'-Dianthrylcarbene was investigated by using laser flash photolysis, conventional flash photolysis, and optical modulation spectroscopy.Its optical absorption spectrum was characterized by two strong bands at 355 nm (ε 3.9E4 M-1cm-1) and at 445 nm (ε 2.9E4 M-1cm-1).Although the carbene has a triplet ground state, the rate constant for spin-allowed reaction with oxygen was ca. 5E5 M-1s-1, yet it underwent self-reaction at the diffusion-controlled limit.These unusual kinetic properties stem from the fact the carbene has a structure in which the unpaired electrons are highly delocalized.
