Popis: |
A study of cyclooctatetraenes (COTs) derived from the photolyses of dibenzobarrelene derivatives indicates the formation of two types of COT with different substitution patterns; the structures of one example of each type have been determined by X-ray crystal analyses. Crystal data: T=294 K, Cu Kα, λ=1.5418 A. (1), dimethyl 6-methyldibenzo[a,e]cyclooctatetraene-5,11-dicarboxylate, C 21 H 18 O 4 , M r =334.37, orthorhombic, Pna2 1 , a=18.364 (4), b= 10.485 (3), c=9.031 (4) A, V=1739 (2) A 3 , Z=4, D x =1.28 g cm -3 , F(000)=704, μ=6.8 cm -1 , R= 0.054 for 1303 reflexions. (2), 11-methyl-5-(2-propyl)dibenzo[a,e]cyclooctatetraene-5,11-dicarboxylate, C 22 H 20 O 4 , M r =348.40, monoclinic, P2 1 /n, a=9.121 (1), b= 20.486 (6), c=10.028 (1) A, β=100.91 (1)°, V=1839.9 (3) A 3 , Z=4, D x =1.26 g cm -3 , F(000)=736, μ=6.6 cm -1 , R= 0.043 for 2688 reflexions |