345915-45-9Relevant articles and documents
Molecular saddles. 7. New 9,10-Bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene cyclophanes: Synthesis, redox properties, and x-ray crystal structures of neutral species and a dication salt
Christensen,Batsanov,Bryce,Howard
, p. 3313 - 3320 (2007/10/03)
We report the synthesis of cyclophanes 18-20 by ester-forming macrocyclization reactions of diols 15 and 16 with 1,4-benzenedicarbonyl chloride. Compounds 18 and 19 display a two-electron, quasireversible oxidation wave in the cyclic voltammogram to yield the dication species at Eoxpa 0.52 and 0.47 V, respectively (vs Ag/AgCl in acetonitrile), whereas the 2 + 2 product 20 undergoes a single four-electron oxidation process at Eoxpa 0.51 V. X-ray crystal structures are reported for compounds 18-20 and the dication salt 182+(I3-)2· (I2)0.5. For comparative purposes, the structures are also reported for the precursor diol 15 and its dication salt 152+(ClO4-)2, which was obtained by electrocrystallization. In the neutral cyclophanes 18-20, the 9,10-bis(1,3-dithiol-2-ylidene)-9, 10-dihydroanthracene moieties adopt a saddle-shaped conformation. The overall measure of folding, the dihedral angle (θ) between the S(1)C(16)C(17)S(2) and S(5)C(21)C(22)S(6) planes, is similar in 15 and 18 (87.6° and 83.7°, respectively) whereas this angle is significantly narrower in 19 (61.1°), illustrating the flexibility of the saddle conformation and its dependence on the packing. Dimeric molecule 20 contains two saddle moieties with very similar conformations, θ = 73.4° and 73.1°. The structures of dication salts 152+(ClO4-)2 and 182+(I3-)2· (I2)0.5 reveal that a dramatic conformational change accompanies oxidation of the donor with the dithiolium rings planar and nearly perpendicular to the mean plane of the anthracene moieties. A notable feature of 182+ is that the bridge enforces a fold of 22° along the C(9)...C(10) vector of the anthracene unit. In 152+ there is no fold about this axis, instead the anthracene moiety is slightly twisted with the two (planar) outer rings forming an angle of 7°.
