Unsaturated thiacrown ethers: Synthesis, physical properties, and formation of a silver complex

The 6-, 9-, 12-, 15-, 18-, 21-, 24- and 27-membered unsaturated thiacrown e thers 1-8 were formed by reaction of cis-1,2-dichloroethylene with sodium s ulfide in acetonitrile. Crystal structures of 4-8 were determined by X-ray crystallography, and it was found that all sulfur atoms of 5-8 direct to th e inside of the ring (endodentate), All of the ORTEP drawings show that the re are cavities in these molecules, and the cavity sizes in 4-8 were 1.76, 2.34, 3.48, 4.43, and 5.36 Angstrom, respectively. The UV spectra of 4-8 sh owed absorption maximums at the range of 255-276 nm in acetonitrile, and th e absorption maximums of 4-8 were found to shift to longer wavelengths by c hanging the solvent from acetonitrile to cyclohexane. The cyclic voltammogr ams of 4-8 indicate that the larger unsaturated thiacrown ethers were oxidi zed more easily than the smaller systems, and unsaturated thiacrown ethers were oxidized more easily than corresponding saturated systems. The reactio n of 4 with silver trifluoroacetate in acetone afforded the colorless compl ex Ag-1(C2H2S)(5)(CF3COO) 9. The crystal structure of 9 was determined by X -ray analysis, and it was found that three of the five sulfur atoms bonded to the silver atom.