Molecular saddles. 4. Redox-active cyclophanes by bridging the 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene system: Synthesis, electrochemistry, and X-ray crystal structures of neutral species and a dication salt

Godbert, N.; Batsanov, A.S.; Bryce, M.R.; Howard, J.A.K.

Abstract

We report the synthesis of a new series of cyclophanes 11a-d by ester-forming macrocyclization reactions of diol 9 with the dicarbonyl chloride derivatives of benzene, thiophene, ferrocene, and diphenyl ether, 10a-d, respectively. Compounds 11a-d display a two-electron, quasireversible oxidation wave in the cyclic voltammogram to yield the dication species at E- pa(ox) = 0.70-0.72 V (for 11a-c) and 0.47 V (for 11d) (vs Ag/AgCl in acetonitrile). The raised oxidation potentials for 11a-c reflect the reduced stability of the twisted dication structure within the steric constraints of the smaller cyclophanes. Consistent with this, the value of DeltaE (defined as E-pa(ox) - E-pc(ox)) decreases (i.e., reversibility of the oxidation process increases) in the sequence 11d > 11c > 11a > 11b as the bridging chain becomes shorter. X-ray crystal structures are reported for compounds 11a-d and the dication salt 11d(2+)(I-3(-))(2). (CH2Cl2)(2.25). For 11a-d the typical saddle-shaped conformation of the 9,10-bis( 1,3-dithiol-2- ylidene)-9, 10-dihydroanthracene moiety is observed, with the strain imposed by the cyclophane ring being accommodated in the structure of the bridging unit. In the dication 11d(2+) both dithiolium rings are planar and the anthracene unit is essentially aromatic, with the conformation of the bridge basically the same as in neutral 11d.

Citation

Godbert, N., Batsanov, A., Bryce, M., & Howard, J. (2001). Molecular saddles. 4. Redox-active cyclophanes by bridging the 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene system: Synthesis, electrochemistry, and X-ray crystal structures of neutral species and a dication salt. Journal of Organic Chemistry, 66(3), 713-719

• Journal Article Type: Article
• Publication Date: 2001-02
• Journal: Journal of Organic Chemistry
• Print ISSN: 0022-3263
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 66
• Issue: 3
• Pages: 713-719
• Publisher URL: <Go to ISI>://000166943800011