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Structures and photochemistry of 1,5-disubstituted dibenzobarrelenes

TitleStructures and photochemistry of 1,5-disubstituted dibenzobarrelenes
Publication TypeJournal Article
Year of Publication1996
AuthorsJones, R, Rettig, SJ, Scheffer, JR, Trotter, J, Yang, J
JournalActa Crystallographica Section B-Structural Science
Volume52
Pagination151-158
Date PublishedFeb
Type of ArticleArticle
ISBN Number0108-7681
KeywordsCRYSTAL-STRUCTURE CORRELATIONS, PI-METHANE PHOTOREARRANGEMENT, SOLID-STATE PHOTOCHEMISTRY
Abstract

The effect of 1,5-disubstitution on the photochemistry of 9,10-ethenoanthracene-11,12-diesters has been studied and correlated with the crystal structures determined for several derivatives; photoproduct structures have been established from a crystal structure analysis of one of the products and from NMR correlations. The crystals studied are: (1)-Cl, dimethyl 1,5-dichloro-9,10-dihydro-9,10-ethenoanthracene-11 ,12-dicarboxylate, C20H14Cl2O4, P2(1)/n; (1)-CN, 1,5-dicyano derivative, C22H14N2O4, P2(1)/n; (1)-CN.0.5p-xylene, C22H14N2O4.0.5C(8)H(10), P2(1)/c; (1)-CN.xxylene, C22H14N2O4.xC(8)H(10), P2(1)/n; (1)-OMe, 1,5-dimethoxy derivative, C22H20O6,

; (2b)-Cl, C20H14Cl2O4, dimethyl 1,5-dichloro-4b,8b,8c,8d-tetrahydrodibenzo [a,f]cyclopropa[c,d]pentalene-8c,8d-dicarboxylate, Pna2(1). The dibenzobarrelene molecules all have geometries and dimensions similar to those of related materials. In particular, the orientations of the two ester groups in each molecule differ, one being in general almost fully conjugated with the C(11)=C(12) double bond and the other almost non-conjugated. Relationships are sought between the ratios of the two regioisomeric photoproducts and molecular and crystal structures; both electronic and steric effects are considered, but no one effect seems to dominate.

URL<Go to ISI>://A1996TZ49400019